Windows 1o will not recognize that I have Flash installed when I try to use it. It's in the 'apps' screen, but it won't let me use it as a default. I use it to watch aircraft maintenance (EAA.org) and photography education videos B&Hphoto). Everything worked fine until I upgraded...as far as I'm concerned Win 10 [watch it]! How do I revert to Win 8 or 7???