Select BPM mode below the "START" button. Enter (or type directly in BPM) the tempo at which you usually practice your scales or sixteenth note sequences. Select "4" in the window below the note icon. The app displays the duration in milliseconds for each note.
Fine-tune the duration in milliseconds (in yellow) to stay within your learning zone: for example, if it's too fast, increase the millisecond value in 5-millisecond increments until you reach the upper limit of your comfort zone.
Change the number of notes per beat whenever you wish. You can create custom programs by tapping the icon in the top left corner.
By tapping the "bookmark" icon, you can save your current settings to retrieve them later by tapping the "history" icon.