A new update from Amazon adds some welcomed features to the Kindle Fire, including password-protected purchasing and new parental controls. With the 6.3.1 update, owners can lock down specific content libraries, such as movies or music, and disable access to the device's Silk web browser. The update is roughly 199MB and can be downloaded to a PC and transferred to a Kindle Fire via USB or users can wait until it is automatically pushed to their device over Wi-Fi. The update page also highlights features added in March, such as the ability to post passages from books on social networks and extended movie rentals. For instructions on how to install the update, visit Amazon's support page.