I have searched for info on your issue and it seems like it might be a bug with your OS (operating system). To fix this problem; launch Firefox and move the maximized window to your second monitor then open another instance of Firefox and maximize it on the first monitor. If that doesn't work, try installing the latest updates for your system. If even this fails, then contact Apple about your inquiry as they are probably the only ones to be able to help. I hope I could help a bit and wish you the best of luck!

After you moved it to the second monitor, did you maximize it first before you restart your Firefox?

I am using dual monitors, if I move FF to any of my monitors and maximize it there, then close it. When FF restarts, it'll open in the same monitor from the same monitor it was on.

See also:

• http://kb.mozillazine.org/Corrupt_localstore.rdf
• https://support.mozilla.org/kb/Toolbar+keeps+resetting

You may need to disable hardware acceleration to make Firefox work properly with a multiple monitor setup.

• Firefox > Preferences > Advanced > General > Browsing: "Use hardware acceleration when available"

I restored my version to 11 and everything works as it was before. So I don't think that it is due to the OS. Somethings not right in the new release.

I also tried the 13b version of Firefox, same issue.

I'll stick to the 11 version until a new version corrects this issue.

Thanks for your help.

Just to give further details: First, my confige is with OS X 10.7.3 and FF12.

None of the suggestions help: There appears to be no localstore.rdf anywhere, or none that Finder can find. And not allowing hardware acceleration doesn't help.

When starting FF, always one window starts on the main monitor. If a previous run of FF had multiple windows, and all those windows were on different monitors (none in the main monitor), on restart of FF, all windows appear in original monitors, except for a random one, which, no matter what monitor it was on before, now opens in the main monitor.

I have been running FF under 10.7.3 for awhile now, and this never occurred. It was just last week when I allowed FF to update to 12 that this started happening.

I too have the same problem on OS 10.6.8. I downloaded Firefox 11.0 and that version opened correctly on the secondary monitor the very first time. It's interesting that it was able to recognize which screen to start on without even going through the steps to open, close and reopen on the desired monitor. Evidently, version 12 made the internal setting but chose to ignore it.

It sure would be nice to have an option in preferences something like:

• Open new windows on the same monitor as last used
• Always open new windows on primary monitor
• Always open new windows on secondary monitor (if available)

Update: Drat! Did an update thinking it would take me to the highest version of FF 11 and it took me to 13. It also ignored which monitor windows should open on. Back to 11... [rolls eyes]

I had this issue with Firefox 12 on OS X 10.6.8 and now still have the issue with Firefox 13 on OS X 10.6.8. Previously, this was not a problem with Firefox 11 and before on OS X 10.6.8.

SUCCESS!

I've been getting the FF13 beta updates hoping for a fix. Today it took me to FF 14.0 and windows now open as expected on the correct (external) monitor.

BTW No OS update has taken place since this problem surfaced and was resolved. I'm still on 10.6.8.

@TheCheezWhiz:

Thanks for the update! I guess those of us that don't want to run the betas will have to wait about 5 weeks for the FF 14 to get released. But at least it will be [and hopefully stay that way] fixed!

What the...

After two days of working fine it has reverted to the same old problem. The first window upon launch and ALL new ones now open on the laptop's screen. Nothing changed with the FF or OS versions.Tried switching it to the external monitor with drag, maximize, close - no joy.

I'm back to wishing for a preference setting to lock MY preference rather than accepting FF's flawed preference.

Update: It has now magically returned to proper behavior. Nothing was changed. So this is what insanity feels like.  ;)

That's so weird!

Firefox 14 on OS X 10.6.8 is still working for me with windows opening on the correct monitor.

I first started experiencing this issue when I upgraded to FF12 and it now continues with my additional upgrade to FF13. When I first upgraded, I was using 10.6.0 and then went to 10.6.8 - no change. The piece I want to add, that I haven't seen addressed here, is that while links within emails and webpages only open new windows in the primary (laptop) window, clicking on links from the bookmarks toolbar do correctly open within the secondary (aux. monitor) window.

Looks like I'll need to revert to FF11 until FF14 is released.

Thanks to all for their constructive input on this!

I've updated to the Beta version of FF14 and now the bug is fixed. In the released notes it was found that the bug was on FF and not in Mac as suggested before. So I went to the Beta version and now all is good. Waiting on the final release but so far no bug.

Thanks, LordVader2k! Just DL'd FF14 and it works great.