I have a S7 that has mad burn-in/retention.. sucks, but all my Samsung phones end up with it :/ not sure if my keeping the brightness at 100% all of the time has something to do with it. Give this burn in tool a shot and see if it helps.
https://play.google.com/store/apps/details?id=mobi.xperiacle.multiwindow.enable
You can try this app, it mostly works but sometimes breaks apps. If the app it processed doesn't open, just uninstall it and install again from play store to make it work.
Edit: Just realized i set my reddit app wrong and i replied to a 4 month old thread :o But maybe it helps you or someone else, so i'll leave it here :)