Hi Kaarlo,
as I understand all Yamaha's models work pretty much the same way as long they have the same functions.
There are little differences between them depending on how the menu and tabs are displaying on the screen and which button to hit in each step but the "philosophy" of how things can be done is the same.
So if a user "move" between these models PSR-S,Tyros,A 3000,Pro 9000 and Genos the majority of doing things are familiar to him and how things can be done.
I have learned doing things on my s750 by reading plenty of posts in the forum concerning other models and got helped this way.
https://www.psrtutorial.com/forum/index.php/topic,42733.msg337855.html#msg337855I have just found a way to do it on keyboard.
1.Press song and select the midi file you wish to change
2.Function --> F --> song creator
3.Press mixing concole
4.Change the volume of the channel
5.Press escape
6.You are back to song creator now to the REC MODE
7.Go to the 2nd tab called Channel
8.Navigate down to the 5th line called Setup
9.Under setup is an execute order, press it
10.To the right you see save button,press it
11. Save the midi with a new name.
On transpose function never transpose channel 10 is the drums.
A midi file is based on pre-recorded notes and orders so it's not always that easy to alter things with just one "click" for each function of the midi file.
If I understand correctly when you are saying "on the fly" you mean when you are playing live in from on an audience?
The only way I can think of to change the octave of the voice for a part while the midi is playing ,
is by choosing a voice that you have in the user area and will be in a different octave but i don't know how convinient that will be if you are playing live at that time.
Have in mind that a midi song can play in any machine that has a program to read midi files and will use the voices that the machine has.
So the same midi will use different voices on a Tyros 1,Genos,Dgx 200,Synthesia,Windows media player,Cubase,Korg PA4x,Korg 600,Casio etc. and that is the reason that it will sound differently in each one of them.