I have installed the lateset reader dc version from adobe and isntalled on three new laptops. On all three adobe was not an option to select as an application for pdfs. If I would go into "Set Defaults by App" its not listed in there either. On 2/3 laptops I was able to set as default after re installing for a 3rd time. But on one there is nothing I can do that seems to get it to work. Have updated to lastest version of windows 10.