Whenever someone says this pistol shoots high, low or whatever, the first thing I think of is trigger pull. It may seem odd that trigger pull can cause a pistol to shoot consistently off target but it's often the case. The best way to eliminate that possibility is with a shooting rest that locks the gun into position. But that's something most of us don't have and a good one is pricey. Barring that, I suggest letting someone who you know is a good shot shoot it. And even they may have a problem with a bad trigger. If you can master a long, slow squeeze, not pull, but squeeze until when the gun fires and it surprises you, you might find the gun shoots better than you thought. The other thing I recommend is to randomly load some snap caps while range shooting. If you notice your gun dipping in any direction other than on target when you come across a dummy round, you've identified the problem which is known as flinch.
These are good things to try before changing your sights. However if all that's good and you've got reliable ammo, then your sights are probably the culprit.