How do I make screen arrangement permanent?

What do you mean by "screen arrangement"?

the position external display doesnt really matter, as an amd hardware developer, i would suggest u check for updates for all of the drivers but there should be an option to LOCK ARRANGEMENT as thats wat i have done, i have 3 apple displays connected to my mac and it deosnt change positions after rebooting.

How do you "Lock" Arrangement? Thx.

It used to work automatically like this here, without any "lock" option. But since April he keeps forgetting the arrangement. Really annoying. Currently running 10.6.8.

I've had a similar issue after upgrading to 10.8. I've run multiple displays on various Mac setups going back to OS 7 and I've never had this problem. I think it has to do with the OS not "saving" the preferences or reverting back to some random setting. Try zapping the PRAM. It seems to have solved the problem for me – at least the last few days/startups...

Here is a reply I posted about Dual Monitor problems on another thread, whereby Mountain Lion forgets the arrangment of the monitors, I wonder if a similar approach may work with your particular case?

🙂 Possible Solution.... needs testing, but initial trial has been successful. Does this work for anyone else?

There are two .plist files I have identified which record the screen arrangement:

1. /Library/Preferences/com.apple.windowserver.plist (top level library, not user library)
2. ~/Library/Preferences/ByHost/com.apple.windowserver.FE******-****-****-****-**********2E.plist

(user library, where *** are unique code) I think the first drives the system arrangment (e.g., login window at startup etc), and the second is a user's own setup.

1. I modified the screen and menu arrangement through System Preferences, which modified file (1).
2. Using a text editor I copied and pasted everything into a new blank document and saved as com.apple.windowserver.plist

   then duplicated the file and named it as per file (2). *even though there were some minor differences.

3. I backed up and deleted the windowserver plists from both the system and user preference (ByHost) folders, including the lockfiles.
4. Moved my new documents into their respective folders and rebooted... windows appeared where they were supposed to. (I should mention that I moved the screen and menu arrangement back to the 'wrong' way first, which showed me that the files had indeed altered the arrangement).

The question is - will this now hold?

Perhaps locking the file / changing the permissions to prevent the system updating it might help IF the problem reoccurs?

Unfortunately, the solution above (rewritting the pref files) did not work for me 😟. Here's hoping 10.8.3 has a fix.

After you have arranged the displays the way you want them, restart and reset your PRAM.

http://support.apple.com/kb/HT1379

You may have to do this process - arranging and restarting - twice.

10.8.3 came out today and no fix. I still have this problem...