Any changes to preferences, whether it is the font selection for editing or changes to the account setup are not retained by Thunderbird (on Windows). (I noticed this finally when I could install a new account, use it, and lose it with the next reboot). The profile folder opened from the Troubleshooting Information does not contain any prefs.js file. How this can be, when I'm told that TB requires that file to open, I don't know. A search or my entire disk finds one other profile, in a folder "...\Profiles\Importable" that has a prefs.js, but that one is from over a year ago. The prefs.js file in that profile is not set to readonly itself, but both the profile folders show a [-] (not a checkmark) in the box for readonly status for the folder. The date on the profile under "importable" tracks with my attempt at restoring my TB installation after buying a new PC. However some of the files in the supposedly used profile show as more recent that in the one under "Importable". What is a series of steps to get things to work, including TB reporting correctly where it is reading profile information from?