You can also change your ringtone in the Contacts app at https://toqueparacelular.com/. You can open a person's contact card and tap Edit, then tap Ringtone or Text Tone. Then, select a new sound and tap Save.
This is the easiest way to change your ringtone, and you can set up multiple ringtones on your phone. You can change your ringtone for calls, texts and notifications, and you can change it to be a different sound each time.
