The SC2 Pedometer comes with a 7 Day memory log. You know you are on the memory log screen if you see a little Day 1 on the top right of the screen.
If you don't see a person on the left of your screen, the step sensor is paused and no activity will be recorded. See how to activate step sensor.
The pedometer is designed to have the screen on all the time, it won't use any more power than a digital watch when idle.
To advance from one screen to the next, press the MODE button.