Canon SPEEDLITE EL-1 Advanced User's Manual page 146

2.
Set the flash mode to <
Press the joystick up, down, left, or right, or turn <
< >, then press the joystick vertically.
The receiver unit's flash mode is set automatically during shooting,
controlled by the sender unit.
3.
Set the firing group of the receiver unit.
Set the firing group (A, B, C, D, or E) for all the receiver units.
>.
146
> and select