Amazon Kindle HD - Allow the installation of application from unknown sources
When you need to download apps or ebooks for your Amazon Kindle Fire, you will normally go to the Apps menu > Store. Some apps are not available on the Store and can only be downloaded from the publisher's website. In order to download and install such apps you will need to enable a small setting.
Pull down the Quick settings menu.
Tap on More.
Go to Device .
Toggle the Allow installation of Applications switch to On.