I have never built his kit, but I suspect that the seats are sitting where they're supposed to. I don't think they're supposed to go right down to the floor. Take a look at this picture:
![](../../../i3.ytimg.com/vi/iveSPDw7ONc/0.jpg)
Note how the bottom edge of the seat appears to be well above the side consoles. IIRC, you get pilot figures in that kit, yes? Try a test-fit with one and see whether it looks like the picture.
Jessica