How to switch Intel HD graphics to AMd randeon

Hi all

Hello, everyone. I recently bought a Dell Inspiron 15 laptop. It came with a built-inAMD Radeon(TM) HD 8670M 2GB DDR3 graphics card. All the games(LOL, DOTA 2, DMC)  that I have tried seem to be using Intel HD 4000 graphics instead of AMD Radeon(TM) HD 8670M 2GB DDR3 I have also assigned High Performance (via switchable graphics) to the games, but they still run using the Intel HD 4000 graphics. My question is, how can I switch Intel HD graphics to  AMD Radeon 8670M? I have searched everywhere on internet, but was not able to find a exact solution. Hopefully you guys can help me out..

Thank you