No order changing, modifying, or setting aside a previous order of the juvenile court shall be made either in chambers, or otherwise, unless prior notice of the application therefor has been given by the judge or the clerk of the court to the probation officer and prosecuting attorney and to the minor's counsel of record, or, if there is no counsel of record, to the minor and his parent or guardian.
Ca. Welf. and Inst. Code § 776