You can switch profiles from the lock screen, add a custom image, and you can also manage content for child profiles using the Amazon FreeTime app.

Each profile maintains personalized settings for things like email, social network accounts, the home screen carousel, book and movie locations, gaming levels, etc. To setup profiles on Fire tablets, open the settings menu and select Household Profiles. To setup a profile on a Kindle, go to Settings > Registration and Household > Household and Family Library > Add a New Person. With child profiles, adults manage all the content available on that profile. With adult profiles you can share content after authorizing two separate Amazon accounts. You can create profiles for up to 2 adults and 4 children. You can use the Manage Your Content page after setting things up on a Kindle or Fire tablet, but the option doesn’t exist until you add a new Profile on a device first.

The main thing is the process has to be initiated from a Kindle/Fire device itself you cannot setup Profiles or Family Sharing from Amazon’s website. Since the update, there’s been some confusion about how to setup Family Library and Profiles to enable sharing.

How to add kindle device