It's different on my Roland Synth. Velocity is Note On, or Note Off, that is all. Volume is Control Change 7, and Expression (which may be velocity to you or a plug-in perhaps) is Control Change 11. But I do not work with MIDI anymore, and haven't for over 10 years. I think there should be a view where you can get want you want up, and use the pencil and if really good, go right down the line at the point you want the change and all of it will change except hard to run down a straight line if that is what you are trying to do except for a few along the way. My lines tended to be kind of a little bit wavy, but then listening to it, it did not make all that much difference and where it did could be corrected once again.