At the moment I could not find these buttons in the available commands for MIDI or keyboard mapping. I will bring this to the developers to see what we can do.
Regards, Adam @Mixvibes
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RoJeC is correct and I had forgot to mention previously, you can use the x2 button on the bottom of the Keyboard and MIDI mapping pages to duplicate a default mapping which will be unlocked and customizable.
Adam @Mixvibes
For support requests, you can check out the FAQ and reach our support staff at this page. Thank You! Team@MixVibes gives no support on the forums including via PM