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For Mac OS updating, we go to System preferences..
Then, you see this screen, if there is a notification at software update.
You click on the software update.
You can see an update to MacOS Big Sur. You click to ‘Upgrade Now’.
If you are on a more recent version of Mac OS, please follow these steps:
1. Click on the Apple symbol, then choose 'About This Mac'.
2. Choose 'Software Update...'.