https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=22605
download the proper version of intel hd4000 driver. The link above might help otherwise look for the correct version of the driver
the hd4000 itself is not a dedicated video card. It uses the shared system memory and computes graphical tasks. So I am not sure if you can essentially change the amount of dedicated vram since you dont have any dedicated video card