Yamaha KX61 opens "Add instrument track" w. wrong key

Hi,

Might be a stupid newbie problem.

When I press the C3 key on my KX61 midi controller the “Add new instrument” panel opens up in C6. Where do I disable this, rather stupid, hotkey?

Btw, the regular “Add instrument track” button maps just fine on the KX61.

Via whatever Remote is enabled.