No password Thunderbird

Somehow I have accidentally set Thunderbird to open without a password. It's wonderful! It was a royal pita! Now in case it changes back, or if a zypper dup changes it back, I'd like to know how to do it on purpose. I have no reason to need a password for my email. I have no secrets on it, and no porn. If someone should get in and read it, so what? And there's nobody here to read it but me anyway. --doug