For about a year I've been trying to understand why the 10th doctor's theme was so sad 9's was creepy and 11's was up beat and happy so why was 10's sad

What are you talking about, what theme? TV? Movie?

The current incarnation of Dr. Who.

Did you watch any of the doctor who with Tenant as the Doctor? Towards the end he's fighting with his powers, responsibilities, impotence of his power, and inability to change what mattered to him. In my opinion at least. He's got the internal struggle and turmoil, and it just spilled out. It was almost as if he was a teen growing and maturing.

The current incarnation of Dr. Who. Did you watch any of the doctor who with Tenant as the Doctor? Towards the end he's fighting with his powers, responsibilities, impotence of his power, and inability to change what mattered to him. In my opinion at least. He's got the internal struggle and turmoil, and it just spilled out. It was almost as if he was a teen growing and maturing. I have watched his entire run and that's a good answer