I have the 12 inch and love it. So many pieces need to be turned to cut around and it works great.
Just enough hold to keep it from running away yet turns easy.
I dont understand what the problem is, mine works perfect. You just turn the top part not the whole thing. It is really simple to use. It is two pieces the top one turns and the bottom has a small hole in it for the top to sit in. You just turn the top one.