You know not every lyrics in songs is completely standard. Sometimes the sentence in lyrics start showing before the same sentence in song for few seconds, sometimes after the same sentence in song for few seconds.
Therefore, is it possible to set two button to sync the lyrics? One button is to make the lyrics show earlier for 0.5 seconds, the other is to make the lyrics show later for 0.5 seconds. If we press the button twice, it will make the lyrics early or delay to show for 1 second.