Syncing music across all devices.
I am prompted to sync my music Library so I can select favorites from Apple Music. I understand all my personal music will disappear. Is that true?
iPhone 17, iOS 26
Hopefully all of the music you have on your iPhone is also stored in the Music app on your computer. What should happen when you have an Apple Music subscription and enable Sync Library on your device is that you get asked if you want to merge or replace what is on the device with whatever is currently in your cloud library. Choosing Merge should keep all of the songs you currently have on the device. When you enable Sync Library on a computer existing content is always merged.
Apple Music is a great service, but it isn't a substitute for maintaining a proper backup of what is on your computer and in your library. It is too easy to remove content from Apple Music and have it removed everywhere at once, with no corresponding undo function. When you decide to cease an Apple Music subscription you also need to make sure that all of your non-subscription content is safely downloaded before you turn it off and stop paying.
tt2