There is a way to adjust the tension. If you look at the picture you will see a little screw that is have circled in red. Pop off the the little corner at the bottom of each side to access the the screw. There is a screw on each side of the window. Tighten the screw to adjust the tension.
There is a lot of information in this link as well: https://cloud.nucamprv.com/index.php/s/6eyDJQ9rNdRqBzd?
For towing or storage we recommend having the blinds/screen open (windows uncovered). If you leave the blinds/screens closed they can start to lose their form over time.