Custom ringtone problems HTC One SV

[gracence]

I don't know what has happened here but this is driving me nuts! I am unable to choose any other ringtone for my contacts other than the stock tones that came with the phone. If I do assign one of my mp3 files(from almost any folder) to a specific contact, when that person calls it plays the Sense ringtone that came with the phone. I have no clue why it plays that tone out of all the stock tones available! The sense tone is not set to any of my "defaults" or contacts! When I look at that contact it says I have a song assigned as their ringtone but that is not what I hear when they call. I have tried full songs from my music list, "ringtones" from zedge, and ringtones from another app as well. When I choose one of these options I notice that they show up in my system settings ringtone folder and I can choose it if I want to. It just plays the sense tone instead when the phone rings. I have a feeling this phone will only play ringtones from a certain location but I don't know where. Can someone please help??? I am aware this could be human error here. I enjoy customizing my phone and I am afraid I may have made a mistake somewhere along the lines. Any info would help!! Thank you all!