Do it the old fashioned way. Don't use the 'X' at top of screen on the App. Whilst in the app then bottom left and select start. That bring you to the app start page. Close the app in the usual way from there. Top left, list, close.
I'm not a desktop freak either and preferred 8.1 as before. I still boot up to the start screen rather than the desktop as you get near instant information on various apps.