Problem
Mac OS Sierra automatically downloads to your system
Cause
Apple pushing their latest OS
Solution
Some users may find that they have a notification in the top right of their display, which says that Mac OS Sierra is ready to install. The notification box will have two buttons, ‘Install’ and ‘Details’ so if you don’t want to install it, then click details which will open the App Store app, which you can easily close.
There are two ways to stop this automatic download of the Sierra installer file, open your System Preferences and then click on App Store.
Option 1 – Uncheck “Automatically check for updates” This will prevent you Mac from checking for any software updates. This option if fine if you want to check for all the updates yourself.
Option 2 – Uncheck “Download newly available updates in the background” This will allow your mac to check for updates, but it won’t download them automatically, as you’ll still get a notification for the relevant update and then it’s up to yourself to download and install the update.
If you want to check your system for the Sierra installer file, it will be in your Applications folder and is called “Install macOS Sierra.app” It will usually be about 5GB in size, so if you want to save space or not install it, you can just drag this file to your trash and then empty the trash.
Hopefully Apple will change the automatic download setup, but don’t count on it happening in the near future.