Can you attach a screenshot? *https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem *use a compressed image type like PNG or JPG to save the screenshot

https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved You may have corrupt '''xulstore.json''' file. '''Close Firefox. ''' Open your file browser to this hidden location: * '''Mac: ''' *~/Library/Application Support/Firefox/Profiles * '''Linux: ''' *~/.mozilla/firefox/Profiles * '''Windows: ''' %AppData%\Mozilla\Firefox\Profiles * *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles * '''Windows XP: ''' C:\Documents and Settings\<user>\Application Data \Mozilla\Firefox\Profiles\ Search for the above file. Then rename or delete it. Restart Firefox.