MacBook Air Doesn't Automatically Update macOS

Although my MacBook Air running iOS 11.6.1 has the automatic update boxes checked for all related options, including Check for updates; Download new updates when available; install macOS updates; install app updates from the App Store; and, Install system data files and security updates, my device does not automatically update itself. Instead, each time I sign in on a new day, I'm greeted with an option to download and install new updates that are 'now available'. What setting am I missing for this to truly automatically update itself besides 'Settings > Software Update > Advanced'?