User profile for user: sjpye
sjpye Author
User level: Level 1
14 points

How do I reset all MacBook Pro display settings?

Summary: I'd like to have my MacBook forget all of its default display configurations when using external monitors, but I can't seem to figure out how to do it. I've used Onyx to flush every cache I can think of, I've tried resetting the PRAM, and I've tried selecting other resolutions in Safe Mode. Does anyone know how to forcibly forget all previously saved display configurations?


Reproducibility and Details: Here's the reason I want to do it. I have a 2016 model MacBook Pro. 15-inch, 2.7GHz i7, 16GB RAM, running High Sierra 10.13.1. I usually run in clamshell mode, connected to an external 4K LG monitor (USB-C to DisplayPort cable). I temporarily used a dual-display configuration, using the 4K display plus my native LCD on the MacBook. I used a resolution tool that I normal use to adjust the 4K monitor based on my mood (sometimes an HD screen in HighDPI is nicer than a full 4K resolution), only I adjusted the MacBook's display to a setting that isn't valid for the screen. The MacBook display turned red, the 4K display went yellow, and the system locked up. Rebooting works, until I plug in the external display. It tries to revert to the same display settings, and locks up again. Running in clamshell mode works fine. Running the MacBook without an external display works fine. It only locks up when I try to plug in the external and use the MacBook display.


I've tried plugging the 4K into different USB-C ports, I've tried just changing the MacBook screen resolution on its own without the external monitor, and I've tried all the stuff mentioned above. The only time it completely freezes up is when I plug the 4K in while the MacBook is open, because it tries to restore the last resolution I attempted, which was a bad resolution. Incidentally, connecting to other external displays work fine, because they have their own resolution pairing defined. Connecting to another LG 4K of the same model makes it fail again.


I'd like to remove that display configuration so that the MacBook "forgets" what the last resolution was, and goes back to using its default. Anyone know how to do that?

MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.1)

Posted on Dec 7, 2017 11:17 AM

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5 replies
User profile for user: sjpye
sjpye Author
User level: Level 1
14 points

Dec 8, 2017 5:00 AM in response to Grant Bennet-Alder

Thank you, Grant! Despite my comment above that I tried making the adjustment in Safe Mode already (multiple times, actually), I'm glad that you reiterated that point here, as it forced me to rethink my steps again. Here's what I had done wrong (aside from the stupid screen resolution in the first place): When I rebooted in Safe Mode, I had unplugged the 4K screen. I was doing that to eliminate all of the variables, but unfortunately, that was eliminating too many variables. I was resetting resolution of the default display, expecting it to stick on reboot. And it was... until I plugged in the 4K, and then it triggered the 4K+NativeDisplay configuration, and that configuration still had a wrongly defined resolution for the Native Display.


What I actually needed to do was reboot in Safe Mode with the 4K screen plugged in to trigger that specific configuration. It of course, booted correctly, and then I set both screens to a different resolution than the default (in order to force-trigger a change), and deliberately chose a resolution that I knew both screens would support correctly. Then, after rebooting, both came up with that new resolution and I was able to then pick the resolution I actually wanted.


Thank you very much for the help, and for triggering the realization that despite trying Safe Mode already, that I actually needed to try Safe Mode in the exact monitor configuration as well and make the adjustment. Everything is back to normal now!

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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
143,241 points

Dec 8, 2017 4:54 AM in response to sjpye

I adjusted the MacBook's display to a setting that isn't valid for the screen.


The "approved method" to fix bad screen settings is to use Safe mode (hold shift at Startup).


Safe Mode has a bunch of things it does differently.

It first does a five minutes or so File System check, before loading MacOS.

It loads the smallest possible number of Apple-only extensions. In particular, it does NOT load the accelerated graphics drivers. This means screen refresh will be quirky and slow.


The other thing Safe Mode does for you is to ignore almost every preference, and use a default instead. This is useful in the case, for example, where you set the screen resolution to something wonky, and you need to recover. Since a default is used, you get a picture. In addition, any changes you make in Safe Mode will "stick" in regular mode after you restart.


The first Restart in Regular Mode takes slightly longer, because some system caches are rebuilt.


NB>> if you do not get a nice, pleasant picture in safe mode, ignore this post and go back to what K Shaffer said.

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User profile for user: K Shaffer
K Shaffer
User level: Level 8
36,144 points

Dec 8, 2017 5:01 AM in response to sjpye

There may be a 'dual graphics' issue involved in your situation, so if your

MacBook Pro 15-inch device has dual GPU, it may be favoring one at

the expense of the other. There had been some earlier advice on how to

choose a workaround to troubleshoot issues or failures in dual graphics.


However there may be something else going on. The graphic card status

or to see if your unit has this hardware, would be a start. You may need to

seek the help of hands-on Genius at Apple store, or an Authorized Apple

Service Provider through an independent service & sales Apple shop.


Sorry to not have an answer to your issue.

Good luck & happy trails! 🙂

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How do I reset all MacBook Pro display settings?

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