If making adjustments doesn't actually adjust anything, you have a stuck/broken scope.
The parallax setting on low-end optics is often unreliable. It may not be 100 yards just because the dial says so. Two things can sometimes be helpful, though I don't find either of them to work easily in all cases. One, try turning the objective until the scope gets blurry. Remember that setting. Now turn it the other way until it gets blurry. Let's say it gets blurry at 50 yards and 175 yards. The approximate correct setting for that yardage would be half way between those numbers, approximately 125 yards. Even if you're actually at 100 yards, the true parallax setting is closer to 125. The other way, is to set the parallax way off, say 250 yards if you're at 100, and look through the scope while adjusting the parallax and moving your head slightly. The whole idea of an adjustment in that it stops the reticle from moving about based on eye position. When the reticle stops moving, you are at the right setting, no matter what the number on the dial says.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.