Every time i need to install Adobfalsh ?

In my acer laptop , if i want to see videos through youtub i need to install adobeflash player every time. I can see Adobe flash player in my application list , still it says you dont have adobe flash player. Then i have to reinstall existing one and download new one. If i restart my laptome it will repeat the same .Really i am fedup of this problem. Pls help me out with some solution.

Thanking you in advance