HI and Welcome to the forums,

 Some things about collections......an unpaid CA is scored the same as a Paid collection.FICO sees a collection as a collection.

 Recent collections can hurt a FICO by 80-100pts in the beginning,then they tend to hurt less and less as time going on.
 I would suggest working on the most recent CA first, because they are the ones hurting your CS the most.

The OC and a CA can both report on the same debt.When a OC reports a past due debt, it dings your CS(credit score).
Then if a CA reports on the same debt, it ding your CS even more.

Debts are either assigned to a CA or sold.If assigned the OC still owns the debt.
If sold, the OC changes the balance to $0 and the CA is the one you have to deal with.

Study the Common Abbreviations  or make a copy to put next to your computer, so you'll know the way we talk around here.

Suggest reading the  The Son Of Credit Scoring 101. and What Steps Do I Take?Do I DV?PFD?

Oh and 2 very important dates to know........the DoFD ( date of first default) on each account.

Second date is your states SOL (statute of limitations), or just tell us what state you live in.