OK OK OK
We will try to get this fixed. Its not as easy as it sounds but we will try to get this working better. Folks above are on the right track. There are a few tricks that can help.
1. Make sure the nut inside the seat is upright with the teeth up and the hole showing.
(a trick we use is to shove a piece of foam under the nut to hold it in place while putting the seat in. I usually use a screwdriver to shove it under the nut.)
2. Put the seat in. I try to have the nuts in somewhat the same position in the tracks of the seat.
3. Line up the holes.
4. Stick a big screwdriver inbetween the top of the seat and the boat right next to wear the back band bracket will go. (this lets the seat and bracket move around much more easily)
5. Line all the holes up. I use an ice pick or small long screw driver to line up all the holes. Take time to make it perfectly lined up. It works best for me if I do the opposite side from where I am standing. Just works better for me.
6. Drop the screw straight down through the holes and turn slowly and vertically with a screw driver. Lots of folks have problems if they try to do this with a drill.
7. Tighten down until its tight. It can seem threaded just on the edge of the slot but if you crank it and it gets tight you will be good. Then loosen a couple turns.
8. Repeat on the other side. One trick if you can't get the hole lined up side to side of the boat is to put a wedge behind the tower or a prop to spread the seat. I have a tall hammer that fits the space pretty well. (if you have extra hands they can hold the seat in the right place.
A couple other thoughts on this.
I like the 1/4" longer screw idea.
Its a good thing that the outfitting is fitting tightly. The reason it doesn't fit as tightly as in your boat is because as you paddle the boat stretches some. That is the main reason for different fitting between your old boat and a new shell. All boats stretch or change shape a little after a good bit of paddling its much more evident in river runners and creek boats.
Point taken and we will try to address, thanks for the feedback.