Welcome the the wonderful world of integrated graphics chips in laptops.
As trad said, there will always be a portion of the system memory that is taken and used as shared memory with the GPU. Even if the integrated graphics has it's own dedicated memory.
Only way to get more RAM is to have more RAM in the system, or for the CPU in the system to not have any integrated graphics and only have the dedicated GPU but that's a pretty rare thing to find.
If you want more RAM, then you're just going to have to purchase an additional stick to add into the laptop, and you will have to open the laptop up to put the RAM in.
Or, if you have a specific model laptop that doesn't have a free slot for RAM upgrade, then you'll have to buy larger sized memory and replace the memory you have.