Thank you for reply again.
That's interesting: somehow I was thinking about it. No, I do not use styles or sequences at all, I only use different instruments in scrolling (one by one, one after the other) and I can arrive up to ten/twelve in the same song.
So, assuming that in the same arrangement program I can only have two instruments (Upper 1 and Upper 2, because Lower has only the left side of the keyboard), I should use up to 5/6 style programs - but this would not be a problem.
The question remains: could I go through them with a simple button-push?
If you can give me a helping hand in this, you will not only have my own gratitude, but also the one of my companions, who do not stand any more my pieces of cellotape changing from song to song and slowing everybody's work.