How to set up the RT52 dual PTT radio's Backlight?

Retevis RT52, as the amateur radio, you can set up the backlight when you need, this video will help you with this function.
What're the highlights of this RT52?
1, High-capacity battery 2200mah, long standby time.
2, Dual PTT design: No need to swift the channel to press the main and Vice PTT to talk.