Save the song file to your phone
Open your phone’s Settings
Tap Sound and vibration or Sounds
Tap Ringtone
Tap Add ringtone or Custom ringtone
Select the song from your files or music app
Confirm and save the selection
Set the song as the default ringtone
For iPhone, use GarageBand to create a ringtone file
For iPhone, sync the ringtone through Finder or iTunes
For Android, place the audio file in the Ringtones folder if needed
Restart the phone if the ringtone does not appear