Hi,
is there any possibility to reprogram the parameters of fibaro switch, that I can use on S1 a toggle switch and on S2 a momentary switch? as far as I see in habmin, in parameter 20 I can set it only for both S1 and S2?! 
thx in advance
That would be very counterintuitive in use. Besides, this Fibaro device is built into a wall box, behind one switch. Having 2 buttons behaving differently, is confusing.
Please check the wiring options in the Fibaro manual. I’m assuming you’re using a Fibaro FGS-223 Double Switch 2. See page 7.
In the illustration at the bottom right, you see that you can operate 2 lights with 2 buttons.
Page 9 details what you can do, either with 2 momentary switches or with 2 on/off switches.
Page 18 describes parameter 20 which always applies to both switch channels (S1 and S2).
So, in essence, what you want to do is not possible. You can however opt to use two single Fibaro switches and set one to momentary and the other to toggle switch mode.