You should understand that old, unpaid bills may be depressing your scores, but paying them off may not improve those scores. In other words, the damage has been done. You may be able to reduce the impact if you can persuade the collectors to remove the accounts from your reports in exchange for payment, something known in the collections industry as “pay for delete.” But you probably can’t erase the late payments and charge-offs reported by the original creditor before the accounts were turned over to collections, and those earlier marks against you are even more negative than the collection accounts.
That’s not to say you should despair. Over time, your credit scores will improve as you handle credit responsibly. But you shouldn’t expect overnight miracles.