Co2 level and beer head quality

I have a six keg kegerator with 4 kegs currently hooked up. I have the pressure set at 10 psi. When I pull the first beer it has a nice thick creamy head. If I continue to pull more beers the head gets smaller and smaller. I do have all the kegs coming off the same regulator at this time. If I let it sit for a little while and pour another one the head quality returns. I’m baffled as to what to do to make it more consistent.

It sounds like the head is being caused by the beer warming in the tower/at the tap. As it warms its ability to hold dissolved CO2 is reduced, comes out of the beer, and provides you a fluffy head. How long are your beer lines?

My lines are about 6’ but they are completly inside the kegerator. I have Perlick taps that go through the door so only the tap is not cold