Backup & Reset - Denwa Communications DW-820 User Manual

2) See the music list in App, select and press a music, and then In the pop-up menu
options, select "Ringtone" -> "Phone"
4.14 Backup & Reset
1) Click Setting ;
2) Click "Backup & reset";
3) Click "Factory data reset";
4) Click "Reset Multimedia Terminal"
5) Click "Erase everything".