By default my modulation joystick (up/down) controls the dynamic expression.
How do I change that so that my after touch key controls the dynamic expression instead of the joystick?
FYI, I am playing the VSL with Korg Trinity (controller), GIgastudio (sampler) & Nuendo (sequencer).
You can change it in your sequencer for individual instruments but I find it far easier to use a midi editor in front of the sequencer and change it in a translation map. MidiOx works great and it's available for free (donations welcomed).
If you don't already have it you'll want to download MidiYoke (same site) first, and then MidiOx.
It has instructions and a forum for support at this link: MIDIOX