Putting a jumper on E1 pins 1-2 enables flashing the ME firmware. It also disables ME, if the system is restarted with the jumper on pins 1-2. That is why the initial position is pins 2-3 so ME is enabled. Jumper position 2-3 enables ME, but does not allow flashing or updates, so that is why the jumper has to be moved to flash ME and then moved back to enable ME.
Make sure the system is off when moving the jumper, because the jumper position is only recognized when the system is powered up.