After selecting Remove menu audio, right click the title button. Does it show Edit menu background as one of the options? Select that option. On the Timeline view of the newly opened window, click on the object in the Video track. Copy it and paste as many times such that the total duration of the video track is as long as the duration of the intended audio. Now, add the audio in the Music track. Then press the Back to menu button. Just an expanded version of what was already advised to you above.