No, the court doesn't have jurisdiction over you once you hit the age of 18.
The information contained in my post is intended to convey general information. It should not be construed as legal advice or opinion. It is not an offer to represent you, nor is it intended to create an attorney-client relationship.
In the state where I practice, as a general rule, no. In certain circumstances in Kentucky (sexual offenses being the underlying charges), the Department of Juvenile Justice theoretically can continue supervision, and I have seen them do so.
If the violation occurred prior to your 18th birthday, the Juvenile Court still has jurisdiction over the violation. However, contact your probation officer, as they will probably have the case closed since you are no 18 years old and outside of the jurisdiction of the court.