|"the max should be 2048 MB.. what to do??"|
I just explained it...what it is that you don't understand? The onboard video has 256MB of it's own dedicated memory, but it can "borrow" more memory from your 4GB of system memory as it needs it. The technology used for borrowing is called "Hypermemory" & it kicks in automatically...there's nothing you need to do. And just so you know, it doesn't stay at 2048MB, it constantly borrows & returns memory based on the graphics load.
Why would you want 2GB (2048MB) of graphics memory anyway? 256MB should be enough for most uses, including gaming. The HD3200 isn't all that great for gaming anyway, regardless of how much memory it has. It's considered a Class 3 card (1 being best, 5 being worst) & it ranks 98th out of 170 notebook graphics tested:
As stated in the following link, "older games like Doom 3 or Quake 4 should be barly playable":
Which would you prefer...4GB system RAM w/256MB video, or 2.3GB system RAM w/2GB video? Most people ask how to disable Hypermemory so that there is no sharing of the system RAM.