Signed out of games

this comes up with each game he tries to play

This can also happen with a bad internet connection, check your home network.

what error does he get when trying to sign in.

he has already done that but it still wont work. he has tried contacting the microsoft team as well for support but they just tell him to restart his PC and say that, that will fix the problem but it hasn't.

best thing to do is click the three dots top left and sign out, then sign back into the store with your microsoft account and try again.