System Preferences on your Mac
System Preferences is where you personalize your MacBook Air settings. For example, use Energy Saver preferences to change sleep settings. Or use Desktop & Screen Saver preferences to add a desktop picture or choose a screen saver.
Customize your MacBook Air. Click the System Preferences icon in the Dock, or choose Apple menu > System Preferences. Then click the type of preference you want to set. To learn more, see Customize your Mac with System Preferences in the macOS User Guide.
Update macOS. Click the System Preferences icon in the Dock, then click Software Update to see if your Mac is running the latest version of macOS software. You can specify options for automatic software updates.