You know how each Transformer has Strength, Endurance, Regeneration, Firepower and Skill that you can level up as you go? Well, when my Optimus Prime levels up, only his Strength, Regeneration and Endurance are displayed as skills that can be leveled up. But say, I want to increase his Firepower, can I not do that? Can I just increase his Strength, Endurance and Regeneration? If not, please tell me how I can increase his other abillities.