Thunderbird is completely unreadable because of the small font size. None of the drop down menus provide a way to adjust the size and of course some genius programmer decided to make the add on Theme Font and Size Changer incompatible with current renditions of Thunderbird like 68.1.2 for Windows. (The add on does however still work on the MAC, thank heavens). I am not a programmer but certainly there has got to be someone within the community that has come up with a fix for this problem. Please let me know what the fix might be. The best fix is releasing a version of Thunderbird that re-enables the older add on to work.