To Self-install Apple System Updates
If you have received a notification window announcing "Important macOS Updates are Ready" and have chosen to defer the installation, you can run the update manually at your convenience at any time before the follow-up notification appears.
- Wait until you have received the first notification window announcing "Important macOS Updates are Ready."
- Select either 12 hours or 1 day in the drop down menu, and click on Defer.
- Please be sure to save your work and close applications and files before proceeding.
- When you’re ready to update (but before the 12 or 24 hours are up) click on Apple Menu (top left corner of desktop)
- Select App Store...
- Click on Updates (top menu of App Store window)
- Install all available updates