On your Mac, choose Apple menu > System Settings, then click General in the sidebar. (You may need to scroll down.)
Click Software Update on the right.
To set update options, click the Info button for Automatic updates, then do any of the following:
To have your Mac check for updates automatically, turn on “Check for updates.”
To have your Mac download updates without asking, turn on “Download new updates when available.”
To have your Mac install macOS updates automatically, turn on “Install macOS updates.”
To have your Mac install application updates from the App Store automatically, turn on “Install app updates from the App Store.”
To have your Mac install system files and security updates automatically, turn on “Install Security Responses and System files.”
Click Done.
To receive the latest updates automatically, it’s recommended that you turn on “Check for updates,” “Download new updates when available,” and “Install Security Responses and System files.”
Note: MacBook, MacBook Pro, and MacBook Air must have the power adapter plugged in to automatically download updates.