Update (sorry

) - still getting severe problems signing in on the chromebook, though the tab the account is synced with (and that needs no password sign-in - it's pre-logged) seems to sign in OK.
I keep getting failed sign-ins (ie nothing happens - no notice of a bad password or anything) and have to make repeated attempts.
I think it might have something to do with the syncing of the outlook account with the android tab - if anyone has any clues (suppose I need someone like me using an account across a chromebook and an android tab) would be interested.