ANDROID:

To set an MP3 file for use as custom ringtone system-wide, do the following:

1. Copy the MP3 files to your phone. The stock Samsung Music Player app ought to be able to see the files. Check whether the music tracks appear in the Music Player app.

2. Go to Settings > Sound > Device ringtone. You will see a list of the phone’s default ringtones.

3. Tap the Add button to launch the media manager app. If your phone has several file/media manager apps, select Music Player from the popup box.

4. You will see a list of music files stored on your phone. Select one and tap Done.

5. Your selected MP3 track will now be your custom ringtone. Repeat the same process to add more custom ringtones to the default ringtones list.