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I've been experimenting with external display on my MacBook Air. I had the external display set up as a primary monitor and my Mac's built-in display as a secondary. Then for some unknown reason the external monitor stopped working. It just sits there saying "no signal" but my Mac display stays as a secondary screen. In this case I can't do anything as all the windows remain in the external monitor that is not showing.

When I unplug the external monitor the Display settings change, so I can't revert anything:

enter image description here

So my question - where do they store current display settings? Or, how do I reset them to their defaults?

(I just want to say that this is such a stupid UI if someone has to ask this on a public forum.)

c00000fd
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    I’m unclear about your last sentence: when you unplug the monitor, the settings change so you can’t revert. How do they change exactly? What are you trying to revert to? – Allan May 22 '23 at 17:33
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    I have no way to test this, but I have a hunch it may be part of 'Displays have separate Spaces'. Disabling that might jump the 'missing' windows back into view. [Used to need a reboot] I don't have a dual display Mac running Ventura, so I can't even really look at the possible options. – Tetsujin May 22 '23 at 17:54
  • @Allan: I'm trying to find out which plist they are storing the display settings in. I want to remove anything that was set up in the Displays settings panel. I can't change it via UI in the Settings because when I plug in the external display I can't get to the Settings window, because the external display is not showing (which is the main display) and the Mac's display is the secondary one and I can't get the Settings window to display on it. – c00000fd May 22 '23 at 17:54
  • There used to be an option when multiple displays are connected, 'Gather windows' which would bring both display control panels onto whichever screen you clicked on. There was also an 'Arrangement' tab, from which you could drag the menu bar to whichever display you wanted to become primary - https://i.stack.imgur.com/ljgAX.png – Tetsujin May 22 '23 at 17:56
  • @Tetsujin The UI in settings has been dumbed down to look more like an iPad. So IDK if it's there. But I can't even open the settings window in my screen like I explained above. – c00000fd May 22 '23 at 18:00
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    Yeah, I've seen how they've totally messed it all up ;) I have one Ventura Mac here, just no option to add a second display to try look at any of this multi-screen stuff. – Tetsujin May 22 '23 at 18:01
  • First, it sounds like your external display failed. Leave it unplugged and disconnected from your Mac. Can you access the built in display become the main display? What settings do you want to change/revert at this point? – Allan May 22 '23 at 18:01
  • @Allan yeah, that's another issue. I'm using my flat panel Sharp TV to connect it via an HDMI cable via a USB-C dongle to the mac. It worked just fine. Then I started playing with the Displays settings and all of a sudden it stopped working and just says "No signal" on the TV. My guess is that maybe the refresh rate is off. That is why I want to reset all the display settings. I can't see such option in the UI, but it must be stored somewhere. As for unplugging the external monitor, then yes, the screen on the MacBook starts showing its only screen. – c00000fd May 22 '23 at 18:06
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    It’s not a refresh rate, but a clock sync issue. An active adapter will likely fix your issue. See this similar question/answer about the screen staying blank. Sometimes a restart of the Mac will fix it, other times you have to power cycle the monitor as well. See if that fixes the issue. That said, there’s noting in settings to fix this problem (clock sync) – Allan May 22 '23 at 18:11
  • @Allan: I tried power cycling the TV. It's a smart TV so it's not even easy to reboot it. Maybe I should unplug it for like 30 sec? I also rebooted the MacBook to no avail. What's interesting is that it used to work and then stopped. – c00000fd May 22 '23 at 18:16
  • Power TV and Mac off. Wait (as you suggested), then power on Mac, then TV. You also want to try a different video source (not port on TV) to ensure the TV is working with that input. Also try a different input. – Allan May 22 '23 at 18:20
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    I just realised display settings are in NVRAM… wonder if blowing that at boot might work?? Assuming you're on an Intel, Cmd/Opt/P/R at the chimes then wait until you hear the chimes again. [If it's Apple silicon, I've no idea, sorry] – Tetsujin May 23 '23 at 08:12
  • @Tetsujin yeah, I'm on the Apple silicon. – c00000fd May 23 '23 at 08:24
  • Apparently you can clear it from Terminal in Recovery - but no-one seems quite sure exactly what it controls yet, so caveat emptor ;) https://www.macworld.com/article/676207/how-to-reset-nvram-on-an-m1-or-intel-mac.html also https://apple.stackexchange.com/q/406873/85275 – Tetsujin May 23 '23 at 08:30

4 Answers4

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After some messing around (to overcome the bad UI) I was able to reset it and see why it didn't work. A couple of pointers:

  1. Never ever set the built-in display to anything other than the "main display"!

enter image description here

Otherwise you will screw yourself over if the external display doesn't connect and it is set as the main display.

  1. If you manage to screw yourself out of seeing the main screen, click the Apple logo on the top left corner of the screen that you can see, and pick "System settings". This (hopefully) will open the setting screen in the MacBook's screen, then go to Displays and revert the MacBook's built-in display to the "main display" status (as I showed above.) This way at least you will be able to start an app and see what you're doing. (Apple's bad UI expects everything to happen in the main display, and if you can't see it ... well, you're screwed.)

  2. Finally, the reason why my external monitor didn't work is because the refresh rate was set to something that it didn't support. For me tweaking it down to 24 Hz worked:

enter image description here

As to why it worked and then stopped working ... I have no idea.

c00000fd
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  • Glad that worked for you. But it doesn't really answer your original question : "How to reset display settings on macOS Ventura to their defaults?" – Thinkr May 28 '23 at 12:26
  • @Thinkr it doesn't, you're right. But it may help someone if they get themselves into a similar situation. Otherwise I am somewhat leery about messing with the NVRAM like someone suggested in the comments. It may be the answer. – c00000fd May 28 '23 at 12:29
  • Yeah, might be beneficial to include that in the answer ;) – Thinkr May 28 '23 at 12:30
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The problem you have described seems to be about the same as the one described in If there’s no picture on your Mac after you change the resolution - Apple Support. According to the same article, to reset this parameter, you can :

Reset the resolution automatically

  1. Wait 15 seconds to see if your Mac resets the display resolution on its own.
  2. If the display resolution doesn’t reset on its own, press Esc (Escape) to revert your display to the previously selected resolution.

Or

Reset the resolution in safe mode

If you can’t reset your display’s resolution automatically, you can restart your Mac in safe mode and choose another resolution.

  1. Start up your Mac in safe mode. Startup may take a bit longer than usual, but your display should begin working correctly.
  2. After your Mac starts up, choose Apple menu > System Settings, then click Displays in the sidebar. (You may need to scroll down.)
  3. Click Default on the right to use the best resolution for your display.
  4. Restart your Mac normally.
Thinkr
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I had this problem today as well and was very frustrated by it for several hours. One person suggested a solution where you use TeamViewer to log into the Mac and remotely change the settings while the clamshell to the MacBook is closed and connected to the blanking monitor, but I couldn't get that to work either.

Finally I found a reasonably simple solution that works through the command line terminal here: https://superuser.com/questions/165108/misconfigured-external-monitor-on-mac-os-x-snow-leopard-10-6-3

What you do is delete the following files:

/Library/Preferences/com.apple.windowserver.plist

And remove every file named:

/Library/Preferences/ByHost/com.apple.windowserver.*.plist

You will likely have to sudo as root: sudo rm {filename}

Then reboot your Mac and monitor settings should return to defaults.

I hope this helps someone solve this problem quicker than I did!

snibbe
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SOLVED: This issue is a result of accidentally setting your monitor as your main display, and due to Apple's poor UI, you can only change display settings of your monitor when it's plugged in. This also due to a resolution discrepancy between your main-display and your monitor.

I tried everything to fix this issue, even brought it to the apple store and they were no help. I tried using terminal along with the different restart methods, but this is the best way to fix (It was briefly mentioned in a previous response):

  1. You will need a second laptop/desktop. Can be yours or your friends, they can even help you from their house. Do not plug in the monitor until Step 6.

  2. Download TeamViewer (this is not an Ad) on the first device and the second device, it is free, it is trusted, and easy to install/uninstall. You only need to create an account on the second device, again it's free. This will allow the second device to control the screen displayed on the monitor while it's plugged in despite no signal.

  3. Open TeamViewer and create an account on the second device, no need to create one on the first device. Once the account is created, start a session using the second device.

  4. Open TeamViewer on the first device, and using the session code created by the second device, join the session. Give TeamViewer permission to access your device. Once permission is granted, the second device will be able to control the cursor on the first device.

  5. Open up System Preferences > Displays.

  6. Plug in the monitor and wait for the display to change. You should then be able to control the monitor screen from your second device. In Display > Display Settings, set your first device to Main Display and your monitor to Extended Display.

  7. Finally, find your monitor's display resolution, in my case it was 1920x1080. Then in display settings, under resolution (For your monitor, not your Main-display) select 'Scaled'. Select the correct resolution for your monitor. This should fix the issue.

  8. I would keep TeamViewer running and installed until you have definitely fixed the issue. Once fixed, uninstall TeamViewer if you'd like. Apple Logo > About this Mac > Storage > Manage... > Applications > Delete.

Ryan
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