Nikon D3400 Reference Manual page 169

To Use Description
Rotate the command dial to skip
Skip 10 s
ahead or back 10 s.
Press X to increase volume, W (Q) to
X/W (Q)
Adjust volume
decrease.
Press K or 1 to exit to full-frame
Return to full-
K/
frame playback playback.
145
Recording and Viewing Movies