If you’d like to download at the highest quality available, or conserve space on your device, you can change this setting anytime.
On Android, tap the Menu button on the top left-hand side of your screen, go to Settings > select or unselect Download Premium Audio.
On iOS, tap the My Music icon in the bottom right-hand corner > Settings wheel in the top left-hand corner > Pro Options > select or unselect Highest Quality Downloads.