Changing notes speed
In this article, describes how to change notes speed of game in sonolus
Open level info page and go setting
Open Title → Play → Any server → Level list → Level, then tap settings and open level settings page. (Settings on title screen have different setting elements since level settings actually depends on which game engine it uses.)
Change notes speed value
You can change the speed with changing "notes speed" at here. If you increase the value, it be faster and if decrease the value, it be slower. If you change level play speed, it changes play speed of music.