Question: how to use downloaded song as ringtone on iphone?
Answer: Now that the new tone is on your phone you need to set it as your ringtone. To do this, open the Settings app on your iPhone, then tap Sounds (also called Sounds & Haptics), then Ringtone. Your custom tones will appear at the top of the list, above the default Ringtones. Just tap on one to make it your ringtone.