Normal Process: Passwords can only get updated via logging on to webmail account and making changes. Then you would edit the saved password in Thunderbird or Enter new password at prompt and make sure to select the checkbox for password manager to remember passwords before clicking on OK.

Menu app icon > Preferences > Privacy & Security Click on 'Saved Passwords' Is it completely empty?

Is that because you have set up a 'Primary (also known as Master) Password' ? Is the 'Use a Primary Password' checkbox selected or not ? Do not select it if it unchecked.

re: I don't have this window that appears and ask you to put new password in. When you start up Thunderbird, do you get prompted to enter a password? If yes, enter password, then select the checkbox for password manager to remember passwords

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