FUTABA 16SZ Instruction Manual page 75

Trim change
The Motor function is used when switching the
motor ON/OFF (mostly for motor gliders). For
most EP planes, the throttle can be left as-is when
controlling the motor by stick. This means that the
various throttle-related functions are usable via
motor control.
＜ Linkage menu ＞
76
H/W reverse
This function reverses the operation signal of the
sticks, switches, trim levers, and knobs.
signal, but does not change the display of the
long as there is no special reason to use the reverse
mode.
Tap the channel you
wish to reverse.
Tap the "Yes"
→ H/W reverse