Surely you are frustrated because of the problem but please be respectful in this support venue.

Did it just update entirely on it's own? There should have been a prompt before updating asking for your OK, or a button that optionally asks to be clicked on to do an update.

Either way, please describe what is on the screen or post a screen shot so we can help.

I have the utmost respect for the volunteers handling the support issue. What I have trouble doing is respecting programming that is sufficiently sloppy that simply rebooting a computer is taken as permission to upgrade when, especially when, the program was set to "Ask" mode on update. I consider the issue solved, I deleted everything except the mail folder I set up for archived messages on a different hard drive, and the profile files for the 13 email accounts, which I then copied to an external drive (as I trusted the uninstall as far as I can throw anyone's uninstall), ran Revo Uninstaller and stripped out everything and spent a good chunk of Sunday resetting all the email accounts. Yes, I lost email messages, it is to be hope nothing terribly critical and all of the calendar entries (fortunately, I rely on a paper calendar for most things). The important ones will send my reminders from the corporate server so that is likely to be irrelevant in the short term. And now I am exporting every single saved message one by one in EML format and will be moving to, god help me, Outlook or some other system. This new layout is a decided step backwards, at which point I might as well use stupid-Outlook as they now look and work the same. I cannot provide screen shots as by the time I found the secret to asking a question, there was nothing to show and the upgrade was done immediately upon rebooting the entire computer and restarting Thunderbird, no ifs, ands, or buts and certainly no prompt. Such it life.