Child Support Modification in Other States

I have been paying child support and alimony since 2002 based on earnings of $70K year. My actual earnings for the past 14 years have been minimum wage or unemployed. My questions are, is it still possible to adjust my obligations based on actual earnings since I still owe $97K (but believe I have overpaid), and if so, what city should I obtain an attorney, city where I live now (WA state), city where my ex wife filed for attachment of my Alaskan Native Stock dividends in 2007 (WA State) or the State of Alaska? Thank you in advance.