The Practice controls allow automatic tempo increase and transposition at each repetition.
iOS, Android: Tap on the chart, then tap the ‘practice’ button (graduation hat) in the player controls.
Mac: the Practice control sliders are near the bottom of the Player controls when maximised (Player controls show on the right). If you have the Player controls minimised, they are at the bottom but the Practice sliders are not shown in minimised view. View>Maximise Player Controls to show them.
Drag the slider to the left to turn it off completely.
When you select another song, Practice settings will turn off automatically.