Those are exactly my problems as well!
If the rear sight is adjusted to the lowest, it stays put.
However, it shoots too low.
When I adjusted it up to be where I think it should be, it held for one range session.
On the next one, it started shooting too high. I find out the screw is loose, and it does not "click" at all.
Now I can shoot it well if I tilt the slide to see the "path" to the front sight.
Perhaps I do not understand how I am supposed to shoot "the best type of sights, black on black without reference points", I am not the best shooter in the West.
None the less I want the sights, or at least the front one, gone!