Samsung Pay is MST which is more like credit card swipe, and NOT "phone pay" such as android pay or apple pay.
If Samsumg Pay does not work, is it because the cashier switched the terminal to phone pay instead of leaving it in CC swipe mode?
I don't know if this has been posted.
While holding the N7 in landscape mode, you can turn the volume up or down by swiping up or down on the right edge of the screen. Swiping up or down on the left edge of the screen to increase or decrease the brightness.