Hi is there a way to turn off retrospective recording in cubase 11
Not that I know of : in the Preferences>Record>MIDI panel, the minimal amount of events that can be retrieved is 1000. FWIW, there are also four key commands dedicated to its control, including the Empty All Buffer… one.
But beside this, it’s for me one of the greatest Cubase feature (actually, I stick with Cubase partially for this one…), so I am wondering why you would like to ‘turn it off’, as it takes no significant resources here, even when set to its 10000 default value, and it never came in the way until now, when doing any MIDI editing… 
I also want to disable this. For me, I own a expressive e touch se and it is very sensitive and is constantly sending low signals due to the vibration of my desk so when I click record there is always a backfill of automation data.
This facility is seriously messing with my korg kronos combi triggering from a recorded trigger track, making them randomly non-responsive - YES, I don’t want cubase deciding for me what I would like, I want this damn thing turned off !
I don’t understand any of the issues. RetroRecording is just a portion of memory that gets filled with recent midi events. As long as you don’t actively instruct Cubase to do anything with it it shouldn’t affect Cubase at all.
But it seems to on my installation. I start trying to pluck out a melody on my keyboard and Cubase out of nowhere starts playing notes that played 10 to 20 seconds ago. Very distracting to say the least. Maybe it’s something else because it seems to go away after playing for a few minutes.