I have the same problem, and others as well. My back and forward icons are gone. I have remember history enabled as well as open tabs from last time. I've tried a few things including restoring my computer to an earlier time when Firefox worked great, but still have the same problems. When I restart after a system restore, Firefox will give me the "this is embarrassing" window and list my previously opened windows and tabs. I select "restore" but only one window with all the tabs opens, and they all fully function. But for other windows, everything is grayed out. I can't use the "customize function because it's grayed out. This is so frustrating, because Firefox used to be great! No more.

Make sure that you do not run Firefox in permanent Private Browsing mode.

• https://support.mozilla.com/kb/Private+Browsing

To see all History and Cookie settings, choose: Tools > Options > Privacy, choose the setting Firefox will: Use custom settings for history

• Deselect: [ ] "Always use private browsing mode"

Make sure that you do not run Firefox in Full Screen mode with all toolbars hidden.

• Press F11 to toggle full screen mode (Firefox/File > Full Screen)

If the menu bar is hidden then press the F10 key or hold down the Alt key, that should make the menu bar appear.

Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible: "View > Toolbars"

• If items are missing then open the Customize window via "View > Toolbars > Customize" or via "Firefox > Options > Toolbar Layout" (Linux, Windows)
• If a missing item is in the toolbar palette then drag it 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 set up.

See also:

• http://kb.mozillazine.org/Toolbar_customization
• https://support.mozilla.com/kb/Back+and+forward+or+other+toolbar+items+are+missing