Windows 10: can't login to windows 8.1 computer with microsoft account being used on windows 10 computer

I have two computers using the same Microsoft account to login. One of them I upgraded to Win 10 and can login just fine. The other is still using Win 8.1 and I cannot login. I keep getting the message that my password is incorrect even though my password is correct.How can I login to the 8.1 computer? My husband can login just fine on it and there is an internet connection,

:)

 

How to reinstall Windows 10 if my computers used the free upgrade from 7 and 8?

Your ild keys should work but if you registered the key to your online ms persona (email address) it should be tied to your account , install without a key login with your credentials , then activate.

 

How to reinstall Windows 10 if my computers used the free upgrade from 7 and 8?

Will windows 10 still accept the license keys from 7 and 8 now if I reinstall my computer?

Does Microsoft keep a list of users who upgraded to Win 10 using their 7 and 8 keys so that when users need to reinstall windows 10 the old keys would work?

Do I need to call in Microsoft to ask them to activate my Windows 10 when I give them my win 7 keys?

Both computers are laptops. The windows 7 machine had the serial printed on the back, and I needed to enter that when I upgraded to 10. The windows 8 machine had the serial built in inside its boot system so I didn't need to enter the key when I upgraded to 10, but I did manage to write down the keys using a fetcher program.

 

Strange Windows 10 User Account issue.

Unfortunately I had done those steps numerous reboots, it just, reappears for no good reason. The base account isn't even a Microsoft account, it's a local account.

I haven't quite tried the built in administrator account on W10, but so far in my experience on my own computer, the built in account seemed to have absolutely no more control than I did on my own.

It's just strange, I go in, it warns me twice about deleting the account, then it's gone. Reboot, and it's back?

EDIT: Just to specify, both command line and Netplwiz both say only HIS account exists on the computer, it doesn't list this rogue account. This is what I meant in my first post about the fact that even Windows doesn't seem to believe it exists, HALF the time. *Frown