I am afraid @Lorraine341 that the possibility you seek is off the tables for you, since you have already accepted the credits as refund.
From Airbnb's travel credit policy:
"By accepting the Offer you are agreeing that the Offer Amount is in lieu of any refund you might be entitled to receive in connection with cancelling the Qualifying Reservation—whether under the Listing cancellation policy, our extenuating circumstances policy, or applicable law. To learn whether you are eligible for a full cash refund under our extenuating circumstances policy for a COVID-19 related situation please go here. By electing to receive Travel Credit or by using the Travel Credit you are agreeing to these Travel Credit Terms."
https://www.airbnb.com/help/article/2740/travel-credit-terms-and-conditions