There is no way to adjust the speed of the scrolltext. Only for typewriter text you can adjust the speed. Please implement this feature for scrolltext, too.
This is a feature that looks so simple to add (please forgive me if it's not the case) that I don't understand the reason so not add it! I don't like the typewriter mode, I prefere the scroll, but we need a option to set the scroll speed, please review this!