When you move high schools your grades usually do not transfer to the new high school from the old high school.
Your credits do however transfer from your old high school to the new high school but your grades do not.
Basically your GPA or Grade Point Average is not transferred to the new school when you change to a different high school.
However if you have a C or above on your courses then your courses usually transfer to the new school but not your grades.
So you'd have to earn the grades overtime again at the new high school.
So I would not recommend changing high schools or any school unless absolutely necessary or you need to move to a different town or state.
Then it would be worth it to change the high schools.