I used the provided Allen wrench to see if it could be done with that - it can. I would wish that the sole held up longer on the outer heel edge, but I have never found one yet that does this. What I perceived as a slipping up and down at first was just a looser fit and there is no slipping inside the shoe. Outrageous! She will grow into them eventually, but I am going to purchase another pair 1 size smaller (which is 1 size up from her measured foot size), which I anticipate will still be a little big according to how big this pair is, but with some room to grow. If I wanted something different and cheaper, I would have ordered accordingly. Still will by another pair. My husband also uses USB drives with the speaker to play his own tracks and he loves it! A hair bit loose but I can live with that. They fit me like a glove.