I just now stumbled across this. I found content from some long ago forum post, that I have used ever since, to alter the behavior of most/all Native Instruments plugins, like Kontakt, Battery, FM8, etc... with regard to the volume fader within each synth getting reset after I would change it. QUITE frustrating.
SO, what I learned to do, is when I insert an NI plugin, like Kontakt, for each instrument I load, I immediately click on its 'wrench' and click on Instrument Options, then click on Controller, and then remove the check for the box for option: Accept Standard Controllers for Volume and Pan. This seems to stop that behavior or resetting the instrument's volume setting in Kontakt.
Give it a try - if the altered behavior is to your liking, you can save the instrument - (whenever I do this, like if I do this change and/or adjust key switches), I save the instrument with a new name in the same folder as the original, usually adding my name to the front, like saving 'String Ensemble' as 'Bob's String Ensemble').
Hope the above helps - I also tend to do this with Battery and FM8, in addition to Kontakt, as these are likely my most used NI plugins, Kontat for sure being number one, for live performance. (I tend to use EastWest Composer Cloud Plus libraries for studio work, 24-bit samples with 5 mic positions, and well over 12,000 instruments).
Bob Bone