Axel F Ring and Motions sound

When I first set up my doorbell, using the app, I was able to set the "Axel F" ring and motion sound to be played when someone pressed the doorbell, or walked by it. I was looking at my ring tone options and trying out the seasonal tones. When I went to put the Axel F back, I discovered it was no longer there. So my question(s) are: Where did it go? How can I get it back? Thanks in advance.....