Password to access gmail mails fails.
I have changed the password for my gmail account with Google. Thunderbird asks me to enter the password but the login fails.
Alla svar (2)
Your picture indicates the authentication method is 'normal password'. Change it to OAuth2, for the incoming and outgoing, in Tools/Account Settings, and check that cookies are accepted in TB Preferences. Restart TB and enter the account password in the OAuth window to allow TB access.
I had the same problem with a GMail account. After changing the authentication method to OAuth2 I got a popup requesting permission for Thunderbird to access the GMail account. Once that was done it started working again.