If you are baking the pizza at 525° F for 12 minutes, I'm guessing that you are using some kind of pan. Is that correct? If so, can you describe the pan (i.e., material, color, perforated/unperforated, etc.)?
Assuming that everything you did was in order, it may be that the Kraft cheese you are using can't take 525° F for 12 minutes. I have experienced similar problems with cheeses when baking a typical Lehmann dough on a preheated pizza stone. As a result, my practice is to move the pizza off of the stone to a higher oven position for a final minute or two of baking to get better top crust browning. It's possible that I wouldn't have to do that if I had better cheeses available to me where I live (outside of Dallas). Unfortunately, I don't have access locally (without going into Dallas) to cheeses like Grande, Polly-O, Stella, Sorrento, Saputo (any of the many brands), or any of the other brands that are praised by our members. I did have access to the Precious and Frigo brands, but the stores that carried those brands recently discontinued them and now offer only house brands. The lesser brands and house brands I have tried either brown prematurely or break down and put a lot of orange-colored oil on the pizza. Whole-milk mozzarella cheeses tend to hold up better in my oven than the low-moisture part-skim variety.
In your case, assuming that the type of cheese is the problem and not the mode of baking, you might try a different cheese or try putting the cheese on in slices or pieces instead of shreds. Adding the cheeses to the pizza while they are still cold might also help. Otherwise, you might want to try a different brand of cheese.