If you are administering multiple Office 365 tenants, you will be jumping in and out of different client accounts all day long.  If you’ve been working in SharePoint, then go to Admin via the waffle, make double sure where you are!  Why?  Because even if you’ve signed out of one SharePoint environment and signed into the next one, you don’t get signed out of the Admin Centre!  Epic fail on this Microsoft, it’s driving us crazy!  You have to change browsers or open a window in Incognito mode to get out of it.  Clearing the cache doesn’t even always work.  I can’t tell you how many times we think we are looking at one client’s Admin Centre, when we’re in someone else’s! It is very annoying.