Microsoft is making life easier for people who use Office web apps with a work account, but who also need to switch to a personal account or another work account. The major annoyance it addresses is that today you need to sign out of the app and then sign back in with another account. Alternatively, the user might do work from another account in a different browser or device. .
Link: Microsoft is bringing this ‘highly requested’ account switching feature to Microsoft 365 web apps
via http://www.zdnet.com