(C) For Windows ® 8/Windows ® 8.1; Press The Windows Logo Key + P On Your Keyboard; While Holding Down The Windows Logo Key, Press P To Toggle Between The Display Selections - Dell UltraSharp 27 UP2715K User Manual

(c) For Windows ® 8/Windows ® 8.1
Connect the external monitor(s) to your laptop or desktop using a video
cable (DP, HDMI etc.) and follow any of the below setup method.
Method 1: Using keyboard shortcut "Win+P"
1.

Press the Windows logo key + P on your keyboard.

While holding down the Windows logo key, press P to toggle between
2.
the display selections.
Method 2: Using the "Screen Resolution" menu
66  Setting Up Your Monitor Display