I have very low dedicated video memory. How to increase?

Once i played Fallout 4 , even the lowest (best performance ) setting would still make the game laggy.
Processor : AMD A8-5600KAPU with Radeon(tm) HD Graphics 3.60GHz
RAM : 8.00GB (7.45 GB usable)
System type : 64 bit
Adapter type : AMD Radeon HD 7560D
Total availavble graphics memory 4071MB
Dedicated Video Memory 512mb
System videomemory 0mb
Shared System memory 3559 mb

You may be able to increase the dedicated memory through the BIOS, but I doubt it would make a difference. Like RoasterMen said, in the current configuration the system would allocate more (up to "Total availavble graphics memory" 4071MB) as necessary.

well thanks. I guess I just have to buy a better card