[Solved] Sonoff(Tasmota) Dual: Correct usage of external Switches

I’m trying to use external Switches in my Sonoff Dual R2(Tasmota 5.12.0)

Reading the explanation Here,I understood that the connection of GPIO0 and GPIO9 to ground should only be momentarily in order to trigger the relay. In contradiction to that I am observing that the respective relay is switched to the opposite of the actual setting when the connection is held and is returning to the old setting when the connection is released.
Did I misunderstand or am I doing something wrong?

[Edit]: Do I have to Change the “SwitchMode” on the sonoff Dual?

Changing the SwitchMode to 3 solved the issue, however only for Button 0. Now I’m struggeling to find the correct syntax for changing the SwitchMode of Button 1.

SwitchMode 3

results in "stat/sonoff_dual/RESULT = {“SwitchMode1”:3}"
I tried “SwitchMode 3” and “SwitchMode (1) 3”, all returning unknown command.

Found it:
Found the solution:
In order to set the mode for Button0 use:

SwitchMode1 3

for Button1 use:

SwitchMode2 3