System Settings on your Mac
System Settings is the place where you personalize your MacBook Air settings. For example, use Lock Screen settings to change when your Mac goes to sleep. Or use Wallpaper settings to add a desktop background.
Customize your MacBook Air. Click the System Settings icon 
in the Dock, or choose Apple menu 
> System Settings, then click the setting in the sidebar you want to adjust. To see additional settings, you may need to scroll down. To learn more, see Customize your Mac with System Settings in the macOS User Guide.
Update macOS. In System Settings, click General, 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.