My employer has been migrating to another domain for some time. This has been a problem when you have to reset more than one password and your e-mail depends on the legacy domain. I found a way where you have no need to login as UK OR wait for Outlook to tell you you need to change your password.
- Press Ctrl-Alt-Del to view the lock screen menu.
- Select Change a password...
- Type in your UK login i.e. UK\Username
- Enter your old and new passwords.
- Click OK.