to court, then the judge will look at your whole situation and make the decisions that he or she thinks would be best for you.
if things have changed between your parents in a way that affects you or if there are serious problems between you and one of your parents, the judge might consider changing the arrangement to make sure that you are happy, safe and doing and feeling well.
but even if things are not going well with one of your parents, it can still be difficult to convince a judge that things should be changed. sometimes, if you are old enough and mature enough, you can make the changes 