If you ever have a balance on PayPal, PayPal will always take that first, then if you have both a bank account and cc on file, which means your a verified member, then instant transfer (ie bank transfer) WILL always be your primary source. But when you are paying for things on eBay, on the third step, where it says we are going to take XXX amount from your PayPal account, look for a more option link where you can select cc. If you are paying directly on PayPal, look for a more funding options link. So to sum it up, if you are a verifed member, your bank is always default if you have no balance on your PayPal account. If you have just a personal unverified account then you can set cc as your primary. But you will eventually hit your sending limit and then PayPal will force you to add a bank account on file.