Ok. here is your problem. (Two that I can see) One, and the most important.
You aren't following the directions in the owners manual or TM's.
The FIRST thing you do is slide the rope into the FRONT of the windshield from passenger side to drivers side and center it in the track. (I find this easy to do standing in the cab with the top upside down on the hood.)
Flip the top over the cab and start to pull it over the rear top bow.
Slide the ropes into the tracks in the side bows and pull them to the bottom. You may need to go from side to side to do it or you may be able to pull one side down fully and then the other.
NOW you can hook the sides in place on the side bows.
Then tie down the back to the rope hooks.
The second thing I see weird is the use of snaps as rivets in the side clips. That will keep the sides from ever fitting flush and tight. (Unless you can accurately locate and install snap bases at those locations.)
Page 2-176 in TM9-2320-212-20 found on this site
and 2-19 in the operators manual.
http://www.steelsoldiers.com/showthread.php?83365-TM-s-for-the-M37
http://www.steelsoldiers.com/showthread.php?99577-TM-9-2320-212-10-M37-Series-Operator-Manual