Background resets

So i have a Wiko Robby with Android 6.0 and i bought the APP so i can fully changed the layout of my mobile. But each time spend more than 2 minutes using an APP my background imagem just resets to the original one... Can you fix this please?

This is generally not caused by KLWP, do you have anything that could prevent Kustom to work as a background service? Like some system app that wipes background apps or something that does not allow background apps to run?