The child does not get to decide which parent they want to live with. The standard is best interests of the child. The child's preference is only a factor that the court considers. A judge will listen to the preference of a mature 14 year old.
Answer Applies to: New York
I do not know Florida law. It is always up to the court to decide. Some judge may agree to nine years old another younger or older. It all depends on the child and the judge. Not the parent, generally.
Answer Applies to: Michigan
There is no age in the State of Florida where a child can choose where they want to live (except for when they turn 18, of course).
Answer Applies to: Florida
The child's decision does not control the judge's decision. At age 14, the child may request to speak with the judge. I suggest you hire a lawyer.
Answer Applies to: Texas