Please review the below information on how to update your Chromebooks OS.
Check for updates yourself.
Turn on your Chromebook.
At the bottom right, select the time.
At the bottom of the left panel, select About Chrome OS.
Under "Google Chrome OS," you'll find which version of the Chrome operating system your Chromebook uses.
Select Check for updates.
If your Chromebook finds a software update, it will start to download automatically.
Note: If your Chromebook uses your phone's internet connection or its own mobile data, you'll get an alert about how much mobile data it needs to update. You can then stop or continue with the update.