abs plastic headliner installation

Today was the day to put in the new headliner in my 74 duster. ABS plastic covered with white vinyl. I had read on here someone saying they would rather put up a fabric one with bows than an abs. I thought that statement was crazy up until a few hours ago.

The stock one was stiff and i was able to do it on my own no problems.
plastic = flexible flyer pain in the rear.

I read the instructions and it said to use the sunvisors to hold up the front get the back set, then adjust and finish tightening up sunvisors. The instuctions should be good for starting a campfire.

Question i have, is it suppose to fit under the window seals front and rear like the original? I have it stuck under rear window seal. It fits like a saddle on a sow. The front end doesnt appear that it will even tuck under the seal. If it doesnt tuck under the seal, with just the sunvisors holding it up, it sags in the center.

What is the right way and what did/am i doing wrong.

Thanks in advance.