Jody I have/had the same problem, though its comfy and shit easy to use. I found that playing with the bungee cord on the back of the backrest helped can't remember if I loosened or tightened. There's a knob either side of the cockpit rim. You could take off the bungee and see it its better/worse??
Simon, yeah its a piece of string, how fucking easy is that to replace!! Think of it over in Uganda and your backrest gives up the ghost . . . best of luck getting a replacement for rachets
On another note I found the seat itself when brought forward tends to slip back so you really have to tighten the nuts. If you do bring it forward keep an eye on it by marking the central piping.
Sean
ps Kylie whatever you get its a
playboat of course its not going to be comfortable