Maybe if you have time you could draw a diagram of it to bring home?
I know it's computerized and you just touch it, but learning where evryone on it is might help.
I once worked in a store as a cashier (Zayre) before they had computerized cash registers. We had to punch one button and put in the style number (for inventory I guess) and then another to put in the price. There were rows of O, 1, 2, etc.
If you didn't remember to change back to money from the style number you ended up with a grand total of a million something (LOL)
Other than that, have you tried looking in a search like google?
You may find a website showing it/telling about it.
Also, have you asked someone else there how they learned it, and if there are any training aides?
I think if you let the customers know you are new it helps, too.
Like joke about it, "wait a minute, I'm new to this". I know, as a customer I have never felt impatient with a newbie who was just learning.
But then I don't think I've ever gone to a MacDonald's- at least through the drive through and gotten what I ordered.
And we went to a lot of MacDonalds in a lot of states.
We did have a big family, though and that might have been confusing with it being a large order.
I don't know how the people who work there do it. I mean as well as they do
Good luck.
~ Carrie