First point - Since a while I cannot simply open Reader by clicking on the program shortcut in the starting page of Windows 10. I have to right click on the shortcut and then action the command Execut as Administrator.
Second point - Openning a PDF document. I cannot open a PDF document located in my library by simply click on its name, as I used to do. To get it done I have to open it through Reader, which is not easy in view of point 1 above.