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

Did you recently install a new extension that might be causing this ?

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

I have same problem after doing update . This new set up is screwy. I am having trouble moving from tab to tab, this is horrible! Do you not listen to what people want? How do I change bookmarks back to white with black letters? The customize screen doesn't work when I press DONE , I have to close tab.

BUT, I tried to download prior version and it messed up something then downloaded latest update and after a few questions in help I have it almost back to what I had.

Adjustments I had made to put tabs at bottom of bars had a bad result with update.