Currently in Apple Music when you sync your iPhone with iTunes, all your music transfers; however, it isn’t necessarily available offline.
This means, sometimes you’re using cellular data to play your own music simply because Apple is trying to save you phone storage.
Here’s the tip on making individual songs available offline, but what if you have a lot of songs you need to add? Here’s how.
How to Make All My Music Available Offline in Apple Music
Tap the three dots next to each Genre and select Make Available Offline. This will still take you a little time if you have many Genres, but it’s a lot faster than by individual song or artist.
Note: some songs not owned by you are not available for download on Apple Music, this only works for songs available for download.