Mirror Display Default Settings

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Level 1

9 points

Mirror Display Default Settings

I use an external display to extend my desktop. For the past year, this has worked as expected, with persistent settings whenever I plug in the display cable. In the past week, however (possibly coinciding with a recent OS update?), the external display defaults to mirroring my desktop. I then have to Open Displays Preferences, select the Arrangement tab, uncheck Mirror Displays, and then rearrange my displays to the desired position. This happens every time I unplug the external monitor and plug it back in again. Are there any other hidden settings that are causing this behavior?

External monitor is an ASUS VS248, plugged in via HDMI cable to Apple USB-C adapter.

Running macOS Mojave 10.14.6 (18G95) on a MacBook Pro (13-inch, 2018, Four Thunderbolt 3 Ports)

MacBook Pro with Touch Bar

Posted on Aug 30, 2019 12:53 PM

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Answer 1

Top-ranking reply

Eau Rouge

Level 8

42,656 points

Aug 31, 2019 12:37 PM in response to reesocles

I think this might be a corrupted system preferences file.

Whilst in Finder click Go in the menubar, now click on Go To Folder,

enter this text.

~/Library/Preferences/com.apple.systempreferences.plist

press Go.

A new Finder window will open with the file highlighted, move it to the Trash

don't empty just yet. Restart your Mac, Once it has restarted open System Preferences

> Displays and set how you like your displays arranged. Now Restart your mac

and see if your preferences have held.

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Answer 2

chris_g1

Community Specialist

Aug 31, 2019 11:35 AM in response to reesocles

Hello reesocles,

Thanks for using Apple Support Communities. It's my understanding that the external display settings unexpectedly default to mirroring. You've done a great job trying to get this resolved! I'm happy to help.

I recommend testing the issue while in safe mode. Starting in safe mode allows your Mac to run certain checks, remove caches, and prevent login items from automatically launching. This can isolate possible third party issues. Use the steps and information in the link below for assistance with safe mode:

Use safe mode to isolate issues with your Mac

If the issue persists, test in another user account. This will help determine if the issue is user specific or system wide.

How to test an issue in another user account on your Mac

Let us know the results. Please include specific error messages and any other troubleshooting steps you may have tried.

Have a nice day!

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Mirror Display Default Settings

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