This is a common issue users encounter in Cubase. To solve this, simply change your input selection for each MIDI track. Under track Inspector, change your MIDI input selection from 'All' to a device that's not your control surface, or 'None' if you don't want them to accept any MIDI input. Alternatively, you could also edit the Cubase Preferences and deselect the 'Record enable selected track' box.
Have more questions? Submit a request