I have WIN 7 and win 10 on my desktop. I use mostly Win 7 and on occasions try out win 10. I always had Thunderbird email. So when i installed win 10, I installed Thundebird there to, in the event that i should receive an email. I don't want to close one OS just to RESPOND to it in the other system. MY point is, I assumed, and please correct me if I am wrong, that I use the same address's and passwords for both of them. But that seems to be a problem at times, especially with my gmail email account. If i change the password on one system, naturally i have to do the same to the other, but for some reason I still have a problem. The one i corrected in win 7 gets me through, but when i use that same password in win 10, it tells me that its wrong. Is there a way to fix this?In Thunderbird you should be able to enter that correct password and it WORK on the Windows 10 system. MAKE sure caps lock and NUM lock keys arent messing with you if the password if correct and its still not working.