Q: Mountain Lion keeps forgetting display arrangement

I agree with you, but as mentioned below, I also think the "fix" or a better solution will come with 10.9. There's already mention that there will be a better implementation of full screen apps for multiple monitor setups. So with this, I can only imagine they will address this bug as well.

I have been doing this stupid thing lately with my system. Works for a while.

I have the 2011 Mac Pro 8-core 32gb ram with 2x 5770 cards. Max display ports is 6. So I have my main monitor (samsung 29" widescreen) and two smaller monitors on the sides. All plugged in via a single card and occasionally the fourth monitor on the second card. But everytime I power down it does not know which one to use.

If you set up the arrangement you will notice the main info pannel is still on the wrong monitor but to bypass this choose mirror displays after arranging them and then unmirror. This resets the saved software code to your configuration.

Next run repair permissions utility on your main drive for permissions. That is probably why you all had mixed results. You had to trick the software into compleatly rearanging the displays.

Unfortunatly it only lasts till next software update. Still have not figured what causes it to recheck the arrangement. But it helps save time.

I use a 27" 2013 iMac and have two old 20" Dell (boo, I know) screens connected to extend my desktop. I also had the issue of screens arrangement being forgotten after a reboot.

But when I log into my system as Administrator and then change the arrangement, it actually stays remembered. Even when I log in with my own normal login name later.

Hope that helps.

Might just be re-itterating what you have said here already, but here goes.....

Got a Mac Pro 2008 model with 2 x 5770 cards (Apple Ones) running 10.8.4 and 6 screens. Had this problem since I bought this unit about 8 months ago and been running latest release all through this period. Screen would lose settings after power off but also just on reboot. Complete PRAM zap, replaced CR2032 battery inside (just in case) worked through all discussed fixes. So reading the thread tonight it appears that our Admin users don't have the rights to change the setting perminantly. So.... I setup the root user account and then logged in, usual problem with screens all over the place. Reset them and then rebooted. All fixed! Have done this a few times now so not just a fluke. Will have to do a cold start and leave the unit off for a couple of days. Have a go and let me know if you also get the same results. Very interested as I was thinking it was my old hardware and it was going to get skipped and replaced with a 2010 12 core but I'm glad I haven't now as I would still have this issue!

Here is the link to setting up root. Usual caveats apply. With great power comes great responsibility Take care!

http://support.apple.com/kb/PH11331

> Will have to do a cold start and leave the unit off for a couple of days. Have a go and let me know if >you also get the same results.

Thank you MrBroons.  I have never used the "root user" but the instructions in the support link you graciously provide seem clear enough.

What I do not understand is the statement you made which I cite above.  Do you mean that shutting down and letting the computer, drives etc. acclimate to room temperature and then turning everything on will be the final verification that your method has "stuck?"  I guess that seems like a long time for things to cool off, so it's got me wondering.....

Hi.

I have the problem happen on a reboot (seemed fixed) but also it can occur after varying periods of the machine being off. Probably not related but you can now see why I replaced the internal battery thinking the settings were stored in a battery backed memory location and as time went on the battery became weaker and the settings were lost.

Well cold start today everything is as it should be, I will report back if it breaks over the next week.

I also had to adjust my 2nd display in the system pref. Was getting quite good at it, but a little annoying.
A thunderstorm was headed my way and i disconnected my iMac from the wall plug.

Some how the deep sleep made the iMac remember my display setup. I seems that way.
Crossing my fingers.

Interestingly although my screens are all organised as normal now (through multiple cold start) they do not retain the information on which program is located in each one when I shut down, they all get jumbled up as per the screen setup... Possibly normal admin users do not have the correct rights to save any screen settings through a reboot. Will have to try again with root, but I'm not keen to keep using root for obvious reasons. Has anyone else solved the problem using the root user to define the correct setup of their monitors?

Still working folks, think I have this one fixed, if anyone can confirm that would be great!

FIXED Six Monitor Layout

Machine:

Mac Pro (2009)

3 x GT120 Video Cards

6 x LG LED Monitors

So I played with this stupid issue for 2 hours and finnally have a fix for this.

I encountered the issue when I migrated monitors and slapped in two more GT120s to compensate the lost of my USB DisplayLink technology.

After setting everything up in the right layout, with the same wallpaper on each, it would get scrambled every time I rebooted. I'd have to re-adjust the layout and the wallpaper everytime. Ugh!!!

I tried ArctiX-Artssuggestion, but it didn't work. I increased the time value to 15, thought it worked, but after the second reboot everything went scrambled again. Got me thinking, something is probably overwriting the prefs files. Let's make them read only and see what happens.

I went into /System/Library/Preferences/ and made com.app.windowserver.plist read only. (Right Click -> Get Info and set to "Read only" for all members>)

For double measure I went into ~/System/Library/Preferences/ByHost/ and made the com.apple.windowserver.XXXXXXXX-XXX-XXXX-XXXXXX.plist also "read only."

I rebooted, and everything came up perfect. I ran a few websites, and rebooted two more times and each time it came up fine. I think I've solved the problem for now. I don't know how this is going to affect re-adjustment of settings in the future. You may have to undo & redo the file permissions. For for me, this is what I use and won't be changing anytime soon.

Hopefully Mavericks solves this silly bug, considering the staple upgrade in multi-monitor features.

Enjoy.

Did you try logging in as root as per my post above. That fixed it for me and there has been no problems since. If I want to adjust the settings I simply log back in as root change things and log back in as normal.

I have the same issue:

• Mac Pro (mid 2010)
• 2x 5770's
• 6 Dell U2412M's 4 running mini display port -> displayport, 2 running DVI
• Monitors in 2 rows of 3

My desired layout is:

[1][2][3]

[4][5][6]

But when this problem occurs I and left with:

[4][5][6]

[1][2][3]

Each row on monitors in grouped together on its own 5770. So in essence, it's as if the two cards are switching order for me . I say this because ML **THINKS** the displays are in the correct order. i.e., when I am on the top row, I have to move the the mouse up when I am on the top row and it comes up from the bottom of the bottom row. Also, when looking at the arrangement in System Prefs, nothing was altered, ML reports to me that nothing has changed URGGGGG!!!!

I have my Mac pro stay on 24/7 365 but it restarts every Sunday morning at 4:00 AM. I skipped Lion and went strait from Snow Leopard to Mountain Lion, and this issue makes he hate it more and more... But so many of my apps now require ML .

When I first upgraded, I would experience this issue only on occasion, say every other month or saw. I didn't think much of it until recently, when it began occurring on EVERY reboot. And worse now, multiple reboots has no effect (it used to fix the issue on the first try) now, I don't know what to do, I am trying this with the issue in place .

Please help us Apple. All our monies already are belongs to you.

I have been having the same problem in two Mac Labs. Not fun when you have to go to the labs each time a new instructor walks into the classroom, big waste of time and a Blackeye for Apple Engineers. I am going to go throuh the forum and see if any of the mirriad of suggestions help. Locking the Displays through root is not an option because each instructor may have a different setup under their login. This used to be a system preferences setting that was saved with each login. Someone at apple must have skipped that line of code in the 10.8 OS.

To re-cap the computer is not recognixing the same graphics card as the primary on reboot. It flip-flops as to which is primary during restart or reboot. As long as the computer is not restarted or rebooted the displays hold true to different logins. The problem almost gives the impression of a Cmos firmware issue, but that would not coinside with the sucess that others have had with the permissions repair and root settings.

HEY APPLE.  FIX THIS PLEASE!!!  Huge energy waste because I can't spend time on this and just leave the whole system running.