Mine has two straps underneath the cover that you can use to adjust the tension. That also is what determines how far up the poles have to go.
here are 2 more pictures of what my cover looks like.
I actually found a picture of what I think it's supposed to look like in the classifieds. When mine is attached, it sits much lower than yours. I'm beginning to think that it is a cover and not a bimini top. Not a big deal since I already have a cover if I need it.
I also have straps attached to the poles but if I stretch them to the snap, the windshield clips pop off, almost like the top is too short. As I stated before, the origional owner never used it, so maybe it's not even the right top for the boat.
I've got all winter to figure this thing out.
Thanks,
Brian