Is everything in a divorce decree final forever?

Your question is way too vague to be answered. If the matter involves children, nothing is written in stone.

If the answer involves strictly a property settlement, you may have a problem.

Several other issues come to mind.:  how long ago ago was it signed?  What were the circumsatnces?  What would you want changed?

If the marital settlement agreement and the resulting judgment of dissolution does not state that certain portions are subject to review and/or modification at a later date, the final decree of a marital dissolution is exactly what is says and means, "final". It cannot be modified or changed later on.