I guess the same person that posted the same question here twice did it. Thunderbird has no "web" links for automatic updates of passwords. Only through a manual update (you must type it in or paste it in) will a password change.

Sorry for the duplicate, when I submitted the first one I got a blank screen with no confirmation.

I was surprised to see the password change, that is why I posted here. I did not type it in or paste it in or in any other way change it.

Until today I had no idea what a "secure mail key" was. I spent a few hours of research to find out. Therefore if I had changed it, even by mistake, I would have entered a normal sign-in password. (I use 12 character sign-in passwords)

Info: https://www.att.com/esupport/article.html#!/email-support/KM1240462?gsi=9MpUOpDZ

https://www.att.com/esupport/article.html#!/email-support/KM1240308?gsi=4Dv7DNKa

Thanks for the reply. I had found those two web sites while doing my research and they both shed light on the new security changes. I still don't know how my password got changed in TB since I never used the procedure (in the linked web site) to generate a "secure mail key".

Snowmantv said

Thanks for the reply. I had found those two web sites while doing my research and they both shed light on the new security changes. I still don't know how my password got changed in TB since I never used the procedure (in the linked web site) to generate a "secure mail key".

I suggest you look to others with access to the physical device then. Because Thunderbird can't do it and no one remotely has access to your computer.