function syncGlobal(hours) {
    var durationHourSelectors = document.querySelectorAll(".amplitude-duration-hours");

    for (var i = 0; i < durationHourSelectors.length; i++) {
      var playlist = durationHourSelectors[i].getAttribute("data-amplitude-playlist");
      var songIndex = durationHourSelectors[i].getAttribute("data-amplitude-song-index");

      if (playlist == null && songIndex == null) {
        durationHourSelectors[i].innerHTML = hours;
      }
    }
  }
Syncs the global duration hours elements.

@param {Integer} hours - the duration hours for the audio.