The Kindle Fire wallpaper rotation is controlled by a system file that can only be changed with root access. Below we’ll look at how to adjust this, which in turn will prevent the Kindle from automatically rotating the wallpaper to a default one each time the lock screen comes up.
What you’ll need to do this:
Unlock your Kindle Fire and open up Root Explorer.
Within Root Explorer browse to the following folder:
Within this folder is a file named wallpaper. Tap and hold down your finger on the wallpaper file.
After holding your finger down on the wallpaper file for a moment an Options menu will appear. Tap Permissions.
Uncheck the boxes in the Write column. Leave the other boxes as they are.
Changing the permissions works because if the Owner and Group are not allowed to write changes to the file, the Kindle Fire will not be able to automatically change the background. The only caveat is, nothing can change the wallpaper including you after these permissions have been set. To change the wallpaper in the future, just reverse the changes just made to allow Group and Owner write access.