Rotating the screen on Mac OS is quick and simple:
- Launch the System Preferences from the Apple menu.
- Hold down the Cmd+Alt keys and click on the “Displays” icon.
- On the right side of the Display preferences, look for the newly visible ‘Rotation’ drop down menu.
- Set to the rotation you want. In this case it’s likely to rotate 90° for the display to go into a vertical page layout orientation.
- Close out the System Preferences to have the settings stay in effect.