a-punkt said

Hello, I use Thunderbird on my Mac 10.11.6. Since the last update of Thunderbird I am trying to set the format for writing mails to 'normal text'. In the settings but it always jumps back to 'paragraph'. There is no 'OK' button that I could click to save the 'Normal Text' setting. This annoys colossally! What can I do there?

There seems to be a problem with TB settings windows being clipped in some OS X setups. Does the OK button appear if you run in safe mode (hold Option when you launch TB, or Help/Restart with Add-ons Disabled)?

Same problem in safe mode. No OK button. What else could I do?

If the problem began with the new version, you could downgrade to TB 52. Not the best solution, but I wonder if there's anything about your graphics setup, screen resolution, display driver etc., that's out of the ordinary. Unfortunately, I don't have a mac to try different options. You could try starting in OS X safe mode, which applies a basic graphics adapter, and see if it makes any difference.

Thanks a lot for your time and help. I don't think it's a hardware problem, since I've no other problems at all with my MacBook and found several postings in this forum complaining about the same problem. I think I'll try to downgrade.......

I presume you're not using the English version of TB, so I should mention that some non-English versions have had issues with OK buttons not appearing or being inoperable. If you're inclined to try the English version, you might find the button issue is not present.