Thunderbird says my AOL password is wrong, it is not

Did you update Thunderbird's stored password to reflect your new, changed password? You can edit the stored password at <Settings | Privacy & Security } Passwords } Stored Passwords>. It might work better if you delete all passwords for that account (there should be at least two) - the next time Thunderbird tries to fetch or send mail you will be asked to enter your credentials and whether you want to save them.

I went through your suggestion but no help. When I try to sign in to TBird, I get this message: "Login to server imap.aol.com with username MilusC@aol.com failed."

Did you delete the current passwords as I described?

Were you asked for your credentials again after that?

Have you confirmed you server settings? I found this page with their supposed correct settings:

https://help.aol.com/articles/how-do-i-use-other-email-applications-to-send-and-receive-my-aol-mail

Do you have more than one AOL and/or Yahoo accounts set up in Thunderbird? If so, and the accounts use OAuth2 as the authentication method, you may have to take some extra steps to make them all work together, as described in this article:

https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo

I figured out, through trial and error, that AOL will create a special password for Thunderbird (or any app seeking access). I did that, entered it into TBird, and now I have access. Thanks your your suggestions. Cal

Interesting. And annoying. AOL's settings page makes no mention of that. Now that you mention it I do find a different page that talks about it:

https://help.aol.com/articles/Create-and-manage-app-password

True to form, they don't reference the other page. They're essentially giving out only half the necessary information on each page.

I have one AOL email account. I've never had to use an app password, which makes me think this is something they have just recently implemented, and that I will need one sometimes soon. That would explain why you just now ran into your situation. At least I know what to watch out for.

I'm glad it's all working for you now.