Body
The Outlook Desktop application for MacOS now has to different interfaces available for users, this article will walk you through switching between these two.
Jump to...
Switch to New Outlook
-
At the top of the Outlook window, locate the Legacy Outlook switch and select it to turn it off.

-
Outlook will now switch to the New Outlook edition, this could take a few minutes.
Revert to Legacy Outlook
-
With Outlook open, locate the Help tab in the menu bar and select it.
-
Then locate Revert to Legacy Outlook and select it.

Additional Support
Further information on New and Legacy Outlook for Mac can be
found here.