I'm going to make my ex roommate and friends pay the utilities on the apt I don't live in anymore
Why do you want to make them pay the utilities there?
I don't need the hassle of paying the utilities on the old apartment.
I can understand where you come from and I agree that you should not be held responsible for bills to a place that you don't live in anymore, but if your roommate and his friends don't occupy that old apartment now, then they should not be paying for it.
My parents say I should cover the bill since the roommates moved out before me, but I'm charging them anyway.
If your roommates moved out first, then the remaining bills are yours and you trying to get them to pay those bills is dishonest. Take responsibility for the charges you rang up with the utility company and pay them yourself.