Control Ableton Live with KeyLab MK II

Hi there,

I just switched from FL-Studio to Ableton, because I read about the good integration of KeyLab and Live.

It seems all knobs and keys are working (I can control volume and pan, scroll through scenes and instruments) but I cannot arm the track selected.
Whenever I press ‘Arm’ (top row of the DAW commands buttons, second from the right) always the same track toggles armed / not armed.

What am I doing wrong?

Where can I find detailed information, which function in Ableton can be controlled with which knobs / buttons from KeyLab?

EDIT:
I figured out that I must press the ‘Record’ button (top row in the middle) to arm the track.
This means, I must select the track (left / right button or buttons below mixer slider) AND press the record-button each time I want to control another instrument.
To me, this does not really make sense. I was used in FL Studio that I can select a channel (instrument) by simply pressing the corresponding mixer-knob and immediately hear the instrument.

Am I still missing something, or is this behaviour to be expected with Ableton?

I guess I didn’t understand the way Ableton works. So I assume, this behaviour is well ‘as designed’ and I will get used to it!