In that case, you may have just bought a pair of poles that can't do what you expect them to, which is to stay tight for an entire hike. The twist and lock poles are kind of an outdated technology as far as poles are concerned. The threads inside the locking mechanism are just asking to get worn out or stripped every time you make an adjustment. It's a catch 22. If you don't tighten the poles tight enough, they don't stay at the height they are supposed to. If you tighten the poles too tight, every time you do the threads will become less effective. I would recommend finding a pair of poles that have the FlickLock system. You simply pull a lever out from the pole to adjust, and then clamp it back down to tighten, much like the quick-release lever on bicycle tires and seats.