Does it really matter that much though? Customers yell about coupons and you nod and move on, that's just the job. I worked a register for two years and the worst I got was a lady mad about an expired deal, I said sorry, she left, end of story. Pushing back sounds great in theory but you're the one still standing there when they ask for your manager.

A register volume setting at 40 percent for two years is wild but I gotta ask, was it really costing you that much? Wrong orders happen at every drive thru whether the headset works or not, people mumble, cars are loud, someone orders a large and you hear a small. Sounds like the new kid from 5th Street just happened to scroll one menu deeper than everyone else. Not sure this is the big lesson people are gonna make it out to be, it's just a thing nobody checked.