User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:126.96.36.199) Gecko/20080702 Firefox/188.8.131.52 Build Identifier: version 184.108.40.206 (20080707) Installed Thunderbird [version 220.127.116.11 (20080707)] on my iMac and have never been able to modify the text in out-going messages. On another iMac that I installed Thunderbird on a few weeks later did not exhibit this problem. Reproducible: Always Steps to Reproduce: 1. 2. 3. Actual Results: Its never worked on this computer - period.
Have you tried deleting and reinstalling Thunderbird on the first iMac? Also, try deleting your profile and see if that makes a difference.
No response in two weeks; resolving as incomplete. Please reopen if you're still having this problem and are able to provide more information/testing.