Arturia KeyStep 37 MIDI Keyboard Controller and Sequencer - Manual (Page 105)

9.10. Working with Device Settings
9.10.1. Common features
Some parameters have pull-down menus with additional options. For example, the
Aftertouch curve has four settings:
The options of each field are different for each parameter.
9.10.1.1. MIDI Channel
Another example is setting the default MIDI channel for a parameter.
The 'User Channel'? setting allows you to change the MIDI channel on which the keyboard
transmits data. When pressing sync
So for each assignable parameter you can choose whether they will be locked to a
particular MIDI channel or will 'float' with the keyboard MIDI channel.
Arturia - User Manual KeyStep 37 - The MIDI Control Center 100