The Demonstration mode options allow you to select how many "pretend" users should be emulated in demonstration mode. You can select from 20 to 250 users, though the standard 50 users provides a reasonable number. Changing the number during an activity may produce odd results for that activity, but can be done.
The master keypad control is replicated in the preferences dialog and in the Master Keypad dialog where you can control what each key does.