If you've had a lot of testing done, and everything is OK, there's not much that can be done to treat it. It might settle on its own as you grow and mature.
I have been evaluated by a doctor and they are not sure what has caused this. They are worried that my heart will beat to fast during physical activity because it is so fast when I am doing absolutely nothing.
That is kind of high, but the number cannot be evaluated without knowing your blood pressure. Dehydration is the most likely etiology, but there might be something serious. Most likely the high rate is compensatory. You need an in-person evaluation by a cardiologist, but I would not be too worried.