When cleaning up credit & paying off old debts, is it better to pay debt in full or can I pay a settlement fee?

My ascendant has dual aged debts, any about 3-6 years old. It would be easiest upon us financially to compensate a marked down allotment upon these debts than to compensate in full. How would profitable a allotment fees upon a debts vs. a flooded change start his credit score? Keep in mind, a intent is to though a home in a subsequent 6 months & content to move his credit manoeuvre up as most appropriate plausible & as alacritous as possible.