problem r5 m230 + hd8500m on a lenovo g50

I have a lenovo G50-45 with this specs

 

- AMD A8-6410 2ghz

- R5 m230 + HD8500m

- 8 GB RAM

and when i try to play watch dogs 2 or another game the game only detects 1 GB of video memorie, i have 1gb on R5m230 and 2gb on HD8500M but i cant use te other graphic or use the two.

PLS HELP i`m from Colombia and me english its bad :S TANKS!