Why do mum and dad fight?
The reason is that Mum and Dad want different things.
Mum might want to do things that Dad does not want to do. Dad might want to do things that Mum does not want to do.
We all change as we get older. You are a different person now from the way you were two years ago. Parents understand how children grow up and change.
Parents grow up and change too. Your Mum is a different person now compared to before you came along. So is your Dad. Both your parents are different people now from when they first met and they might want different things.