I bought some Office 365 license and learned that I automatically got a free basic Azure AD along with that.
So now I joined my first PC to the Azure AD and logged in with an Office 365 user:
%userprofile% turned out to be:
After some googling I found that this is the sAMAccountName (correct?).
I cannot figure out how to change the SAM account name in the Azure AD web admin application. I am missing a page that corresponds to this classical AD dialog:
FirstLast seems like a very inconvenient default because e.g. my last name contains a german umlaut so my userprofile would also contain a special character, which will probably break countless applications.