Failed to meet credits requirements. Need advice

My son did not get enough credits in order to graduate on time (in 4 years)
His degree requires 128 credits, slightly higher than many other degrees that require 120.
He found out a bit too late and now he has to take 2 or 3 more classes in order to satisfy degree requirements. (at least one of the missed classes is not offered in summer so he will have to go to one more fall semester)

I am not panicking, he will take one more semester as part time student, and pay per credit. We have the money to pay for it without need to financial aid, so that’s not a problem

The question is - does he have to make any type of official changes with the Penn state administration? I’m so confused and just afraid that there are some procedures for this sort of thing and I’m afraid that he may overlook some formalities and it will cost him his diploma even after he finished required classes.

I’m hoping that someone who’s been in this situation can provide guidance.

PS. He already went to the office and had his name removed from graduating list so that he can signup for more classes.
PS also his advisor mentioned that he has one credit that could be moved from one of the classes he already passed. And if he moves that one credit then he is only short on 2 classes.
Is this “move” of credit a real deal? Or should he signup for another extra class just as an insurance in case that “moving” of credit does not work?

These all sound like questions for Penn State admin.

Best of luck to you.