Each of the function button works as shown below.
[F1 (LMTrk)]: This displays the track mixer level meter.
fig.12-04(tr_lvl.eps)
[F2 (LM In)]: This displays the input mixer level meter.
fig.12-05(in_lvl.eps)
[F3 (LMAux)]: This displays the EFFECT bus and AUX bus level meters.
fig.12-06(efx_lvl.eps)
[F4 (PRE)] or [F4 (POST)]: This switches the display of the meter showing
the signal level before passing through the fader
(Pre) and after being adjusted by the fader (Pst).
[F5 (F/P)] or [F5 (Meter)]: This switches between the display of the level
meter and of the pan and fader positions for
each channel.
fig.12-07(f/p_lvl.eps)