Flash Player 11.6.180 youtube problem

Hi, I have trouble using the arrow key to scroll up and down on youtube, This problem happened after I upgrade my flash player from 11.2 to 11.6. When I pause or click anything on the flash pane, I cannot control the page using arrow key. The only way is to switch tab. I have reinstall version 11.2 and everytime I want to view any video, the message vulnerable flash player version occured. Please help