Try the following solutions to fix “waiting for change to be applied” error. Do the each solution one by one and check if the “waiting for change to be applied” error is gone or not.

  1. Disable “Find my iPhone” feature in your iPhone.
  2. Uncheck “Sync Music in iTunes” option. Delete all music. Then re-check “Sync Music in iTunes” option again.
  3. Turn off “Sync music”.  In your iphone or iPad go to Usage -> Manage storage and delete music.
  4. Delete all non-music files from iTunes music folder.
  5. In iTunes un-check “Sync Music”. Delete all music using General -> Usage -> Manage Storage. Then re-check “sync Music” option again. In iTunes summary tab, select “Sync only checked songs and videos” & “Manually manage music and videos ” options.
  6. Drag and drop playlist in your iPhone.
  7. Unplug the USB cable when you get stuck on “Waiting for changes to be applied” message. Then replug it again.
  8. In iTunes summary tab, select  Manually manage videos” option. So you can manually able to add music to iPhone.
  9. In your iPhone iTunes app, go to General > iTunes WiFi Sync and choose “Sync now” option.