1. Set the primary display resolution.
- Open the Apple menu
- Open System Preferences
- Click Displays, then Display
- Select Scaled, and choose one of the available options.
2. Set resolution for a connected display.
- Once the display is connected, open the Apple menu
- Open System Preferences
- Click displays, then display.
- Press the Option key while you click Scaled to see additional available resolutions for the secondary display. Then selected a scaled resolution option for the display.