Welcome to planDisney, Kimberly! I also like to purchase onboard credit prior to my cruise to add to my stateroom account. You can purchase onboard credit with a Disney Gift Card (my favorite!) or a 
major credit card up to 3 days prior to your sailing.
Each adult stateroom Guest will have their own stateroom account unless you agree to take care of their charges. If you purchase onboard credit, only you will have access to it. Charges can be made with your 
Key to the World card or 
DisneyBand+. You can view all of your charges in the 
Disney Cruise Line Navigator app and on the television in your stateroom. The credit will also be reflected in your onboard folio. 
When you complete Online Check-In, you will be required to add a major credit card or select cash as your onboard folio payment method, even if you plan to purchase onboard credit for all your expenses. 
I hope this helps you plan your upcoming Disney Cruise Line vacation. If you have any other questions, sail back to 
planDisney, Kimberly.
Adventure is out there!
JoVonn