Add-on icons can be moved around or removed from all toolbars. You can use the Customize feature to hunt it down and move it where you want it.

To start, use either:

• right-click a blank area of the tab bar > Customize
• tap the Alt key > View menu > Toolbars > Customize

Note that all toolbars should become visible during the Customize process, but when you click Done, the ones that are turned off will not be visible. To make a missing toolbar visible, either:

• right-click a blank area of the tab bar > select toolbar
• tap the Alt key > View menu > Toolbars > select toolbar

Any luck?

• 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

Check for problems caused by a corrupted localstore.rdf file if the above didn't help.

• http://kb.mozillazine.org/Corrupt_localstore.rdf