Hello,

Try drag and drop the button between the navigation bar and search bar, then close the customize window.

• Customize toolbars

Also try do this in Safe Mode:

• Firefox in safe mode

It works in Safe Mode, but it doesn't work if I manually disable all add-ons and restart.

Anything else I can try to avoid resetting altogether?

Try disable one test and disable other and test......

This problem can be caused by a corrupted localstore.rdf, try go to your profile and delete it:

• Profiles
• http://kb.mozillazine.org/Localstore.rdf

• if missing items are in the toolbar palette then drag them back from the Customize window on the toolbar
• if you do not see an item on a toolbar and in the toolbar palette then click the "Restore Default Set" button to restore the default toolbar setup

• Firefox menu button > Options > Toolbar Layout
• View > Toolbars > Customize

Thanks Diego!!

The problem was these lines of Localstore.rdf:

   <RDF:Description RDF:about="chrome://browser/content/browser.xul#nav-bar"
                   collapsed=""
                   iconsize="large"
                   mode="icons"
                   currentset="unified-back-forward-button,urlbar-container,reload-button,webrtc-status-button,stop-button,downloads-button,lpt_lastpass-compact-btn,window-controls,social-share-button,tp-notification-popup-icon,pilot-notification-popup" />

compared to localstore-safe.rdf, which was:

   <RDF:Description RDF:about="chrome://browser/content/browser.xul#nav-bar"
                   currentset="unified-back-forward-button,urlbar-container,reload-button,stop-button,webrtc-status-button,bookmarks-menu-button,downloads-button,home-button,window-controls,social-share-button" />

It was probably the entry:

   collapsed=""

telling Firefox not to collapse the buttons into one. I deleted all lines except for currentset and everything was back to normal.

Thanks again.

Great.. I reset them to default, (because there were various buttons missing from Customize), lost more buttons & my browser's even more screwed up. (heck, now I can't even put buttons to the left of the Back button?!) Furthermore, I don't understand the instructions for editing the localrestore.rdf. This happened due to Firefox's automated update to 29.1 on May 12th, 2014. (I can't seem to find the previous version either.. thanks Mozilla, heh)

Can somebody please give me a slightly more in-depth hand?'