Transfer Audio Files from a Windows PC:

  1. Connect the OnePlus to your computer using the USB cord
  2. Enable “File Transfer (MTP)” / “Media device (MTP)” when prompted or from the “Notification” area
  3. Open the File Explorer and use it to locate the desired audio files on the PC
  4. Copy the files and transfer them on the phone storage, preferably in the “Ringtones” / “Notifications” / “Alarms” directories
  5. Once the transfer is complete, eject the phone storage via system tray and safely disconnect the device from the USB cord

Change the General Ringtone:

  1. Open the apps drawer
  2. Go to “Settings
  3. Scroll to “Device” and tap “Sound & Notification
  4. Tap “Phone ringtone
  5. Select the desired ringtone and tap “OK” to confirm
  6. Optionally, choose to turn “Also vibrate for calls” ON or OFF

Change a Specific Contact’s Ringtone:

NOTE: You cannot assign custom ringtones to contacts stored on the SIM card or the device’s internal memory.

  1. Launch “Contacts
  2. Select the desired contact and tap “Edit
  3. Tap “Menu” > “Set ringtone
  4. Select the desired ringtone
  5. Tap “OK

Change the Notification Sound:

  1. Open “Settings
  2. Tap “Sound & notification” under “Device
  3. Tap “Default notification ringtone” and select the notification sound you want to use
  4. Tap “OK” to confirm

See More: OnePlus 3T: Transfer Audio Files (from a PC) and Set Custom Ringtones & Notification Sounds