You can go to Tools|Options|Security|Passwords>Saved Passwords and edit or remove the existing password. You'll need to tell it to show passwords and you can edit the password by double clicking it.

And look for all entries. You will almost certainly have to change the password for both incoming and outgoing.

That is a path I never new existed, and very helpful to know. However, I actually fixed the problem in a more drastic way. I removed my q.com account from Thunderbird and then I added it back. I had to Browse the local directory path back to the original one, because when I recreated the account, Thunderbird created a new one with "-1" appended to the name. Once I did that, everything snapped back into place.

I think Zenos's solution would have been more direct, and I'll remember it for the next time I have a password problem. Thank you!

We do sometimes see situations where resetting an account by reinstalling from scratch is beneficial. With IMAP accounts, you really don't need to do your last step of re-connecting the message store, because in IMAP the messages are stored on the server.

The pain comes from all the little tweaks you might do to select columns, set up filters, associate or de-associate address books and so on, and all this needs to be done afresh if you rebuild an account.

Resetting the password is a relatively quick and easy step. If the account configuration proves to be the real issue then resetting the account can be the quickest way back to normality.

Yes, I agree. Had I been aware of that path through the Options, I would have done that. However, removing and then adding the account back was relatively painless, albeit I admit that it was using a sledge hammer to hammer in a thumbtack. I do have some filters and local folders and changing the local directory path back to the original made everything right again. Thanks again for your help.