GE E840S - Manual (Page 52)

During the video playback, an operation
guide appears on the screen. You can use the
navigation pad to perform the functions ac-
cordingly.
During the video playback, you can use the
Up/Down navigation buttons to adjust the
volume of playback.
During the slow motion playback, you can use
the
Left/Right navigation buttons to adjust
the speed of playback.
Volume will be muted when using the
slow motion playback.