If you're paying off a debt that was sent to a collection agency then don't be surprised if the debt doesn't show as paid when you pay the collection agency off.
Most collection agencies don't even bother to report your paid off debt to the credit bureaus. And you sometimes will have to get a lawyer involved to have the debt reported as paid off to improve your credit score.
But if your other debts are showed as paid in full then it can take a month or 2 or sometimes even up to a year before your credit score can change.