1. Go to System Preferences.
  2. Click on Displays.
    Image
    Screenshot of System Preferences highlighting the Displays button.
  3. Click on Arrangement.
    Image
    Screenshot of the 'Built-in Display' window highlighting the Arrangement button.
    • To show different windows on the displays, make sure the box next to Mirror Displays is not checked.
    • To change the order of the displays:
      1. Click on a screen.
      2. A red border appears on the selected display.
      3. Drag the screen to the left or right.
      4. The result is applied immediately.
    • To choose which display shows the top menu bar and the dock, drag the white rectangle to the desired display
      Image
      Screenshot of the 'Built-in Display' window and the Arrangement tab showing the tiny white bar that can be dragged.