Is there a way I can assign buttons on my midi controller to next and previous presets?
Or even a PC keyboard shortcut. It is very distracting having to grab the mouse and click the small arrows each time.
Preset selection is not assignable in Kontakt.
That's one of the nice things about the NI keyboards, there are buttons and a jogwheel for preset navigation (for NKS compatible plugins)
Best you can do is create 'Instrument Banks'. Not suited for large instruments, but you can't navigate through those anyway.
Assign keyboard navigation to sift through banks.