To set a song as an alarm tone on your iPhone, follow these concise steps:

  1. Open the Clock app on your iPhone.
  2. Tap the "Alarm" tab at the bottom of the screen.
  3. Tap the "+" button to create a new alarm.
  4. Set the desired time for the alarm.
  5. Scroll down to the "Sound" section and tap "Pick a song."
  6. Choose the song you want to use as your alarm from your Music library.
  7. Ensure that the song is downloaded to your device, as alarms will not play songs that are not downloaded.

Keep in mind that each alarm has its own options, so if you want a specific song for all alarms, you'll need to adjust each alarm individually. If you encounter issues with the alarm not playing the selected song, ensure that the song is downloaded and try deleting and recreating the alarm.