You usually just press the green button for credit on the MX915/MX925's or select credit from the screen as it really depends on the merchants configuration. Ingenico has you pressing the red button instead so it can be confusing. Its the same as Apple Pay with a Debit card or a regular magstripe card. (Pin bypass) You don't have to enter a pin if you don't want to and heck at the Nike Factory Store debit even declined and I had to select credit to get Google Wallet to work.