Friends: I was running 91.13.1 for the longest time and upgraded to 128 (Nebula) which is a disaster. So many bugs. I kept saying they ruined a great software. E.g., search was totally broken: take forever and doesn't work. Resizing columns is a pain but I realized 115 was the same way. Challenge: profile gets upgraded too and can't downgrade. But I pulled out backup of a) program b) profile from backup. Replaced everything except the Mail (and its subfolder Local Folders) Replaced the program to 91.13.1 Worked like a champ ~~ upgraded to 115.12.2 - terrible - nicer UI e.g. resizing but same issues as Nebula described above (with columns, search etc.). ~~ downgraded back to 91 - got the profile back upgraded to 102.13.0 Jul 2023: https://thunderbird.en.uptodown.com/mac/download/104978201 (downloaded from: https://thunderbird.en.uptodown.com/mac/versions) ~~~ The designers of this great software broke the UI after 115. Happy to be back at 91.13.1 and won't upgrade for a loooong time, if ever. Best Regards