Sounds like you have a slightly larger sized girth than would be ideal. Are you wearing the spandex sleeves and Retainer Band to help firm up and secure the fit?
Another common problem is not setting up the base band correctly. So we want to eliminate that possibility as well. Just make sure that when you are wearing the inner wear so that you see the top of the logo letters first when looking down, otherwise the silicone ring will be positioned towards the outside of the sheath with a tendency to roll under and the glans to retract back inside.
Also can you tell me what size inner wear you are using.