I deleted my old password in privacy and security and waited for the prompt but the old password popped back up.

Was the password there when you went to privacy and security? I really do not understand this "I had to edit the password before I delete that old password" that make no sense to me at all if you were going to Edit it, just change it to the new value and you are done. The rest of this about having old passwords pop up makes no sense at all as once the password is changed in the password manager Thunderbird has nowhere to get an old password from. I am taking a mad guess this is actually a reply to https://support.mozilla.org/en-US/questions/1572898 which I will further guess has something to do with this missive. https://support.mozilla.org/en-US/questions/1572312 I will not reply to this topic, Please stick to one topic for your information as it is all linked. do not start a fourth new topic. Please explain in your replies what you mean. I have now read all three of these support topics and none of them contains sufficient information to understand what the issue is because you are yet to actually post the error message you get. add to that I can not understand what old password pops up that Thunderbird has no capacity to know and only one place where it can display it for you to see (the password manager where you deleted it) so you are not making progress here, largely because your information is not coming across in a way anyone can visualize.