Edit/Preferences/Security/Passwords/Saved Passwords is the path on Linux. I recommend you delete the passwords, set the authentication to OAuth2 for the incoming and outgoing Yahoo servers, restart TB, and enter the account password in the OAuth browser window. This will store a token in Saved Passwords instead of the password.

Thanks for your reply! I appreciate the quick response!

I did what you said, and that indeed removed the passwords. After restarting TB, though, it did what it did the first time, it had you log into Yahoo and you HAD to agree to let TB access the email account.

From what I can find out, this is because Yahoo doesn't like to let you access their servers except through their browser-based programs. If you want to use a third-party app, program, or whatever to access their servers, they make you agree to access this way, and they make you accept any risk if your account(s) is/are hacked. I hate to tell them, but the only hack proof account is one that doesn't exist.

I do not prefer Yahoo's browser-based interface because they change it every year or so, usually in a way I don't like. First they let you try the new interface, but later they force you into using it. So I think if I want to use Thunderbird, which I do, because it gives me a consistent interface, I will have to put up with their demands, or change email providers. Eventually I might bite the bullet and do just that.

This wasn't the solution I was hoping for, but c'est la vie. Nonetheless, I am grateful for your efforts because the method will be useful to me (or others) if, say, I had to change passwords on one or both of my accounts and then TB would be unable to access it/them.

Keep up the good work! This is why I use community-based software because somebody out there usually knows what I need to know. Trying to get information out of Yahoo about their own programs is like trying to move a forty-foot sponge by kicking it.

your account is set to use oauth. This stores a "key" rather than a password and it can basically be renewed in the exchange with yahoo indefinitely without user interactions. It is not good for those that want to not save passwords. Until they disable it permanently you could use a normal password and jump though the hoops on the yahoo web site to create an application password to use with Thunderbird. But previous posts to this forum would indicate you do a lot of password resetting for various reasons on the yahoo web site to keep it working.