You can use a paypal balance but sometimes the merchant themselves OR paypal require you to add a back up bank or card to verify your paypal account before you can continue.
Also click on the profile tab (icon next to log out) > Click on payments third option along on the thick blue band top of page > second down click on update next to your preferred way to pay and put a dot in the balance option.
Advice is voluntary. Kudos / Solution appreciated.
