Question: how to set default ringtone on note 4?
Answer: Tap edit icon in the top as shown below. Current ringtone is shown. Select the ringtone from the list (which includes the pre-installed Galaxy Note 4 ringtones and all audio files in Ringtones folder) or choose “add” in the bottom (as shown above). Tap “Done” to apply the new customized ringtone for this individual.