Here's how you can change the channel on your Chromebook. You can opt for Stable, Beta or Developer.
1. Go to chrome://help in your browser.
2. Click the More Info link.
3. Select the channel you want to use:
Previously, you couldn’t easily revert back to a newer channel, but Google has changed how the recovery process works. Now, there’s no reason not to try newer code on your Chromebook: It often gives you early looks at new or upcoming features as they migrate up to the Stable channel.More at Gigaom
Additional resources for Chrome OS