This doesn't really need a tutorial because it's super simple, but Eleaf decided not to put it in the manual so I may as well place it somewhere I can find it again.
- While powered on, hold down + and fire button simultaneously until the display starts flashing. From here you can change to display puff counter or seconds.
- Change to the counter you want to reset using + or -
- While the the display is still flashing, press and hold the + and - at the same time until the counter is reset