User manual

Immersive navigation background.The system set multiple colors for the
navigation background to match the color scheme of the popular apps. The
background color is default white, and it will become translucent or immersive
when you open some of the third-party apps.
3.1.4. Volume buttons
Volume buttons give you easy access to adapt over time to a proper volume of
sound. It refers not simply ringer or media, the phone also keeps track of the
volume level separately in headphone, microphone and speaker.