With a few easy steps, you can transfer music saved on iTunes from your Mac or PC to your iPhone. You might need to do this to sync purchased music and ringtones to your phone (since Apple still won't ...
You can add music to iMovie from a variety of different sources, depending on the device and type of sound you're adding.
You can redownload music on your iPhone that you've purchased from iTunes or saved with Apple Music. Here's how to do both.