If you are using an external display, you can see many more resolution options in System Preferences if you know how to reveal them. In System Preferences, Displays, Display, hold the option key and click the “Scaled” selection. This changes what is shown. Option+click it again to switch back. Depending on your screen you may also see a checkbox for Show low resolution modes for more options. On MacBooks and iMacs when you are using the built-in display, this doesn’t reveal anything, however.
Mac Video Tutorials and Tips for Apple Users
