I've recently purcahsed a refill key but have not had chance to use it yet. I know that the refill key shows how much is in the hopper, how much the last win was and volume adjust options. My question is: How is all this shown on the small screen? I know that it will display something like "105 x 20" which means that it needs £20 to be put in for the hopper to be full (meaning the machine has an £125 hopper), correct? But how is the 'last win' displayed and how do you adjust the volume?
I am asking this purley because when i do use it, i want to be quick so i have less chance of being caught and i'm not standing there wondering what all the garbled code on the screen means!

On a side note, i've heard that machines have a system that alerts the bar staff when a refill key is entered. Is this true and if so is it very widespread or is it only used on a few machines?
Thanks in advance. Oli