Could someone give me some helpful hints on modifying child support?

On my financial statement to modify child support, it says anything else I would want to say…I know the ex husband is going to read the paperwork. I actually have alot to say, but will it help my situation…
For example, the ex has not followed anything that the expensive divorce decree contains, from having my son every other week to living in the same school district, to notifying me about job changes and more. Please help me.