Click on Software Update
If you do not see Software Update in the list of System Preferences, you likely have an old OS that will install updates via the App Store
Click the More info link as shown in the image below: NOTE: Until you are ready to upgrade the entire operating system, do NOT click the "Upgrade Now" button
Select all available updates, especially macOS and Safari updates, and click Install Now (macOS 11 screenshot | macOS 12 screenshot | macOS 13 screenshot) macOS 11-12 macOS 13 - 15