When you add your song to YouTab, you can add a lyrics track easily :
1.When in edit mode click on "Tracks" in the toolbar and click the “Add lyrics” button.
2. After you click this button, we will search for the correct lyrics and add them to your song. After adding the lyrics all you have to do is sync them to the music.
The “Add lyrics” will then be disable and the "Delete lyrics" button will then be active fro removing the lyrics.