Wrong section and setting unfortunately. I had a look at the manual for a similarly spec'ed Foxconn motherboard, and if HP used a similar bios with various features/settings b locked as they are known to do then there is a very good chance that there is no way to adjust that setting. From the manual I looked at the onboard graphics settings are under a section called "Overclock Control Center",
with the actual settings in the "IGP Configuration" section,
Let's come at it from another direction and at least see how much memory has been allocated to the onboard graphics. Grab this, GPU-Z Video card GPU Information Utility
and post a screen shot of it please.