Sign into Paypal and then there is a link there to set your account options.
As others have said, change the 'primary funding' option to a credit or debit card number (visa, etc) rather than a checking accout.
Even if your visa is a debit card that deducts straight out of your checking account, it will then go through immediately rather than as an echeck, which can take several days to clear and delay your shipments.