Transfer Audio Files from a Windows Computer:

  1. Connect the OnePlus 3 to your computer via USB
  2. When prompted, enable “File Transfer (MPT)” / “Media device (MTP)”, otherwise enable the option from the “Notification” area
  3. Launch the File Explorer on the PC
  4. Use the Explorer to locate the desired audio files on your computer
  5. Copy the files and transfer them on the phone storage, preferably in the “Ringtones” / “Notifications” / “Alarms” folders
  6. After the transfer is done, eject the phone storage via system tray and safely disconnect it from the USB port

Change the General Ringtone:

  1. Open the apps drawer
  2. Launch “Settings
  3. Scroll to “Device
  4. Tap “Sound & Notification
  5. Tap “Phone ringtone” and select the desired ringtone
  6. Tap “OK
  7. Optionally, select to enable or disable “Also vibrate for calls

Change the Ringtone for a Specific Contact:

NOTE: Custom ringtones cannot be assigned to contacts located on the device’s internal memory or the SIM card.

  1. Open “Contacts
  2. Tap the contact you want to customize
  3. Tap “Edit” > “Menu
  4. Tap “Set ringtone
  5. Select the desired ringtone and tap “OK” to confirm

Change the Notification Sound:

  1. Launch “settings
  2. Under “Device”, tap “Sound & notification
  3. Tap “Default notification ringtone
  4. Select the notification sound you want to use
  5. Tap “OK” to confirm

See More: OnePlus 3: Transfer Audio Files from a PC and Set Custom Ringtones & Notifications