How to increase my graphics card memory?

Hello everyone.

I currently own a DELL laptop Inspiron 15 Intel N5010. I wanted to increase the memory of video card (Radeon HD 5470 512mb) by sacrificing some RAM. As I browsed the internet for a solution most of the posts offered to do that via BIOS setup. The problem is that my computers BIOS setup has no such option (entered by pressing F2 key on startup screen). It barely has any options at all.

Is there any other way to increase my video card's memory, or am I entering a wrong setup?

Thank you in advance :)