The latch (or clamp) is indeed adjustable for the folding bikes!
The clamp needs to be tight in order to ensure that the frame is secure while you are riding, but if you need to make an adjustment, it is easy.
Extend the latch so it is all the way open and look at the latching mechanism. There is a center bolt (that connects the frame and the clamp) that can be tightened. When the bolt is extended it gets tighter, if it is shortened it gets looser. You should be able to twist this with your fingers, but you may need to use an adjustable wrench to tighten it. We suggest that you test the clamp in small increments. The clamp will need a little muscle to close, but cannot be too loose as it does secure the frame. Adjust the arm enough so that you can close the clamp.
We hope this is helpful.