PW dropped continually

This is another post for my months-old problem of Mozilla's T'bird, and before that OEx, "forgetting the Pw for my accounts. It affects both, with no consistency of time, either individually or at the same time.. I must go to AT&T Uverse, the the Pw reset, and then continue until such time as the problem reoccurs.
Sometimes the initial reset does not take, and UVerse troubleshoot has to bump me up to the next level of support.
Last time they said, as did contributors here, clean cookies, cache. Did, even cleaned Grandma's false teeth. Worked for a few days, now the primary account is not recognizing my pw.
AT&T is saying it something with T'bird, which of course they do not support - except for a special fee. T'bird has no customer support, just a forum which has been very little help.
The format of T'bird is quite suited for my needs. I can go to Yahoo directly for my mail, but that is too cumbersome and difficult to navigate, and sometimes there are delays getting all my mail..
Have I encountered a problem from the Twilight Zone, a problem which exists in the shadows of my imagination, but for which their is no solution? Or is the solution simply to pay AT&T more than the hefty charges for UVerse and keep my arthritic fingers crossed? :hammer:crap(
Sarge

 

As one of my grandsons so likes to say, "You got that right."
MS Outlook here I come (hopefully)
Thanks for nudge, been contemplating such for a while

Sarge