（1）Menu: function setting including language setting/ time setting
/firmware update.
（2）Ok: in menu setting mode, it serves as a validation button; in preview
mode, press ok button, it serves as function switch button.
（3）Brightness control: control the light from 0-9 levels.
（4）Return: return to previous menu.
（5）Playback: in preview mode, press this button, it will go to
image/video playback page.
（6）Up: in menu setting mode, press this button to upward navigation;
in preview mode, after pressing OK button, it can adjust the relative
function variable.
（7）Down: in menu setting mode, press this button to downward
navigation; in preview mode, after pressing OK button, it can adjust
the relative function variable.
（8）Front view/side view switch: In preview mode, press this button to
switch between front view and side view lens. (only available for dual
lens model)
（9）Photo/video: short press for taking photo, long press for taking video.
In video mode, short press for snapping a picture.
（10）Resetting: when the monitor does not work for abnormal reason,
press this hole by needle, it will restart.
（11）HDMI: connect the monitor with display by HDMI cable, the image on
the monitor will be displayed synchronously on the display.
