How can I edit my settled divorce agreement if my former spouse is extremely uncooperative?

You can request a modification of child support.  Changed circumstances such as a change in income would be grounds for a modification of child support.

To request a modification of child support, file an Order to Show Cause (court form) and a supporting declaration.  The supporting declaration states the facts in support of your request for a modification of child support and is signed under penalty of perjury.  File these documents with the court along with a proof of service and serve a copy of these documents by mail on your ex.  When you file your Order to Show Cause with the court, the court will schedule a hearing on your request for a modification of child support.

The proof of service verifies the date of mailing to your ex.  You can either use a court form proof of service or you can write your own.  If you write your own proof of service, it just says that you are at least eighteen years old and the attached documents were sent via first class mail unless stated otherwise to __________ (name and address of your ex) on __________ (date).  You sign and date at the bottom.  The date you sign should be the same as the date of mailing and the same date you file your documents with the court.

Before you file your documents with the court, check with the court clerk to be certain you are filing all the required and appropriate documents for your request for modification of child support because the required documents may vary from state to state.