Press the "Windows + P" keys on the keyboard to pull up this menu.
Here you can pick what screen you want the content to show up on.
"PC Screen only" - Will only show content on the main screen.
"Duplicate" - Will show content on all screens/teles plugged into the desktop/laptop.
"Extend" - Will extend the content from your main display to any over displays which you may have.
"Second Screen Only"- Will only dhow content on the 2nd display screen.