Many divorcing couples believe that their case is finalized once a judge signs off on the divorce settlement in their case. This isn't necessarily the case though. It's still possible for each spouse to appeal a judge's ruling. If that's not an option, then they can request to modify their divorce decree.
Although it's possible for a former spouse to appeal a divorce decree, appellate judges seldom overturn a lower court's decision. One instance in which they're likely to agree to hear an appeal is if there were enforceability issues or only one party agreed to the settlement terms. If there are concerns that a judge abused their power or there's a suspected error of law or fact, then they may hear it as well.