how can i change my shared video memory

It sounds as if you have integrated graphics, with the GPU using the same RAM as the CPU.  Therefore, make sure you have open RAM slots in your laptop, and buy some DIMMs compatible with the memory clock speed and bandwidth as your other RAM.  If you don't have any open slots, you could probably replace your current RAM with a new stick or 2 with greater capacity. 

 

EDIT:  i reread your post and I'm not totally sure what you are saying, maybe that you have 64MB total ram of which 16Mb is shared with your integrated graphics controller? in which case, you still probably need more RAM, as your system RAM is mostly used by your CPU. 

my system:

m755 2ghz

512mb ram

64mb video memory (shared)

 

i will max graphic memory using