If you have already installed Samsung Pay on your Android smartphone, you may not be able to make the payment. A notification may appear on the terminal such as «Several cards are available» or similar.

If you wish to pay exclusively with Google Pay:
Select the menu «Settings -> Applications -> Default applications -> Tap and pay -> Select standard payment service», then set «G Pay».

If you wish to use several Mobile Payment Apps (e.g. also Samsung Pay):
Tap on the menu «Settings -> Applications -> Default applications -> Tap and pay -> Select standard payment service», then set «Tap and pay with open applications». In this way you can select the desired Mobile Payment App for each individual payment process.