A background, like the Spring background on a dark gray theme below, adds a little interest to the top right corner of your Office 2013 and Office 2016 programs.
Click File > Account (Office Account in Outlook).
Pick an Office Background from the list.
Every computer connected to your Office Account will use the same background.
Only change the background on this computer
Click File > Options.
Under Personalize your copy of Microsoft Office, pick an Office Background from the list.
Tip: To make a background really stand out, try changing to a Light or Dark Gray Office theme.