Hi, I think this is what you are referring to:

• Customize your New Tab page to hide or display content

• Customize your Firefox New Tab page

If your question is resolved by this or another answer, please help other users by marking the best reply as Solved. Thank you!

Thanks, but this didn't help. I think the problem is with Yahoo, not Firefox. There are no buttons or links to access content, layout, etc. It all started with the upgrade to Big Sur on macos.

Ah OK, so you are using Yahoo for your home page? In that case, if you haven't already, restart Firefox. If that doesn't help, restart your Mac.

Hold down the Option key when you start Firefox to start in Safe Mode. More - Diagnose Firefox issues using Troubleshoot Mode.

If it works in Safe Mode, disable any theme or extensions you have - 3-bar menu > Add-ons > Themes/Extensions, then restart Firefox; now if it's still OK, re-enable them one by one until you find the culprit. You may need to restart Firefox after enabling some extensions.

Try resetting the home page by opening the Yahoo page you want to use and copying the address from the address bar - you can now close the tab. Now open the 3-bar menu > Preferences > Home, and make sure that 'Home page and new windows' is set to 'Custom URLs...' You can now delete the URL that is in the box and paste in the one you previously copied.

No, those tips didn't help. Same problem in safe mode. I'm pretty sure the problem is Yahoo. There are several posts on their support website from people who have the same problem - no tool icon to allow you to change format or content. I guess I'll wait for Yahoo to fix.