Chromebooks should update automatically, but if you want to force it to update or just check to make sure you have the latest version you can follow this guide or click here to watch this short video
- Click the status area in the lower-right corner where your account picture appears.
- Select Settings.
- At the top or left of the page that opens, click About Chrome OS.
- In the “About” window that appears, click the Check for and apply updates button.
- Restart when you see this icon in the lower right corner.
Once any updates are done, you can look in the "About" window to confirm that your Chromebook is up to date.