How do you make a monitor the primary display on a Mac?

monitor primary display mac
Big Mac: make your external screen the primary display

If, like me, you use a MacBook with an external monitor at your desk, you might be wondering how you make that second screen your primary display. It is dead simple, but not very obvious.

Why should you make your monitor the primary display?

External monitors are normally larger than the screen on your MacBook, which means it makes sense to have them designated as the primary display.

The primary display is where most applications and the Dock will open by default. There are certain, stubborn applications and games – such as Civilization VI – that point-blank refuse to run on anything but the primary display.

And in case you’re worried that your Dock or applications will disappear when you’re using the MacBook alone, don’t be. If you’re only running the one screen, that becomes the primary screen by default. It will switch back to your external screen when you next plug that in.

How to make a monitor the primary display on a Mac

  1. Click the Apple icon in the top left of the screen, and choose System Preferences
  2. Click on Displays then the Arrangement tab
  3. You should see a white bar at the top of the display that is currently designated as your primary display. To reassign the primary display, simply click on that white strip and drag it onto the other display.
Mac display options

NOW READ THIS: How do I snap windows on a Mac?

About the author

Barry Collins

Barry has scribbled about tech for almost 20 years for The Sunday Times, PC Pro, WebUser, Which? and many others. He was once Deputy Editor of Mail Online and remains in therapy to this day. Email Barry at

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