Hello @Allison240,
The terms of the pay less upfront option, whereby Airbnb charges the guest 50% at the time of booking and 50% a few days before checkin, state that both payments will be taken from the payment method.
There's no way on the site for guests to change that.
You could try contacting Airbnb support to see if they can accommodate the request.
For information on ways to contact support type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.
