It says in this Microsoft article that there should be a little 'down-arrow' next to my primary email address, when composing an email, to select an alternative "From" address...

http://windows.microsoft.com/en-US/windows/outlook/add-alias-account

However, after clicking "New" to send a mail, there is no 'down-arrow' next to my name or primary email. There is no way at all to change the "From" address when composing a new email.

I have attached a screenshot...

Please advise.