After spending a decent amount of time selling all my crap with multiples in my inventory I came up with the suggestion on swapping the All and Confirm functionality.

Reason being is if you are already punching in numbers you are already using that part of the UI so it should be more natural to go down to the last button of the UI and hit Confirm instead of pressing the button on the controller. This would also make it easier to select all at this point because all you would need to do is press the button Y button.

I've heard similar complaints with buying stuff from a couple friends where they would put in the number and actually go down to where my suggestion would put confirm and they end up buying All The Things! This should resolve that whoopsie as well.

And that's my suggestion!