Audio files

Hi,  I am a new Articulate Studio 13 user, and I somehow keep loosing my audio files.  I save them after creating, but I go back the next day and they are gone.  Also, this is only true for audio files attached to power point slides, it is not effecting any of my Engage interactions.  There is a folder being automatically created that is titled "project content", and I can see sound files in it, but I do not know how to reincorporate them to my project.  Please help!