Check for updates Chrome OS

At the bottom right, select the time  Settings  . 
 At the bottom left, select  About ChromeOS . 
 Under "Google ChromeOS," 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. 
 
 You might need to try to run updates a  few  times because the update may fail on the first few attempts. Press  F5 (Refresh) a few times.