Just Pair the W385 with one Mac or PC via Bluetooth and then Browse the Phone in the Computer. I'm tested on Mac, use the Bluetooth File Exchange located in Utilities Folder and Hit,
1- File/Browse Device.
2- Select your Phone and Clic Browse.
3- You will see a New Window with some Folders, remember Accept the Incoming Connection on the Phone.
4- Open the Audio Folder and just Drag & Drop your MP3 Ringtone, CHEERS...you can also copy all you Stuff located in the Phone like, Photos, Videos, etc...to the Computer just selecting them and pressing Get.
NOTE: Your MP3 Ringtones will be placed in the Default Ringtone Phone Folder, find it and Assign it as Ringtone. 😁