The orders made by a judge at the time of your parentage judgment were based on information that was correct at that time. However, over the years things may change. For example, you may lose your job, inherit large sums of money or move. Some things in your judgment can be modified (changed) by a judge. For example, you might request to change child custody or visitation orders if one parent wants to move out of the area or if the child's needs change; or you might request to change child support if there has been a change in financial circumstances.
It does not matter who files the parentage action. The court does not give any preference to the person filing the case (Petitioner) or any disadvantage to the person responding (Respondent).