You have to file a motion for revision within 10 days of the order being signed. If it is filed 11 days after, the motion will not be heard. There is no standard format for a Motion for Revision nor is there a form. It wold be best to hire an attorney if you are contemplating such action
The information is for general information purposes only. Nothing stated above should be taken as legal advice for any individual case or situation.
If the order was recently made, then a Motion for Revision is properly made within 10 days. If the child support order has been in place for longer and there is a substantial change of circumstances, you may instead be seeking a modification of the child support order. If that is the case, you need to file for Modification for child support and the corresponding paperwork with it. You can find the forms you need by looking up Washington state court forms on the internet. Good luck.