https://www.youtube.com/watch?v=sxal0SxI10w
Software will look different but above should help.
Note that you only have the same VRAM (video memory) for games that matches the smallest amount. If the video card has 2GB and you could only assign 1GB to the APU's VRAM (in the motherboard BIOS) then you can only use 1GB for games.
Conversely if the card had 1GB there's no point (AFAIK) assigning more than this in the BIOS to the APU's GPU.
Also, some games may indicate the TOTAL amount is being used (like 3000MB) where in reality that might be about 1500MB of the same data for both GPU's. That's just a reporting thing but thought I'd say just in case you got confused on that.