The problem is if there's already a custom skin there and you want change for another it doesn't show the skin instead is like you never selected one also if there's not custom skin just a blank skin meaning you no selected one then if you select one will show but after as previously mentioned it doesn't show the new skin you selected from your gallery but if you explore the files you will see that skin you selected after selected other will be there this does happens to me on my ZTE blade v6 plus also there's a video showing what I'm explaining