"Yahoo is [synced] but not Thunderbird"

You mean the yahoo web message statuses are accurate, but on Thunderbird it is not?

I guess you might put it that way , not good with terminology . My android phone and my old Win 7 computer stay the same and what I do on one is the same as if I had done it on the other . As in ; a read or deleted e mail shows the same on both units . When I use the new Win11 computer it has the read as unread and the deleted ones are shown as unread also . I would like all 3 units be the same , read or deleted ones to also show as read or for the the deleted ones to not be there . I am still trying to get the Win 11 computer set up so eventually I will only need the new computer and my phone to agree on what has been read and what has been deleted . Hope this clears up my problem , sorry for not understanding how this forum works , I think Toad-Hall got me straightened out on that score . Now I seem to be in the right place , I am 85 years old and a little slow on how some of these things work . Thanks for your patients !

                        Ken