See if it works like the Bionic: using the stock music player, start playing whichever song you want to use as a ringtone. Then press Menu and you should get a pop-up list of various options, including Use as Ringtone. Click it, and if it works like the Bionic, that song will now be your default phone ringtone. Of course, you can change the phone ringtone to whatever you want at that point, and if you want to use that song as a ringtone for a contact, it will be in your ringtone list.
I would suggest if you can connect the phone to a computer, see if you see a "ringtone" folder in the internal storage space on the phone or the SD card. If you see there, copy the music/ringtone files to that folder.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Give this a Look to help in setting ringtones and other things...
Click on the Links i provided:
this is the Manual For Jelly Bean on the Razr M..