Hi, I'd like to change the default pitch / frequency from 440 hz to something else but I can't find how to do it on the keyboard manual or in the menu.
The S88 doesn't know anything about pitch. It sends only MIDI data to the VSTi it's connected to in the form of note on/off. You'll need to look at the manual for the instrument for details of how to do the pitch change.
That makes perfect sense, thanks for your answer