I have a taurus 24/7 with 3-dot sights. I am wondering how to go about adjusting the sights.

When I shoot from the right hand the grouping is always to the left of center, and when I shoot with the left hand I usually hit spot-on. This is only with this particular handgun. With my revolver this is not the case (nor is it with my friends XD and Glock)

Is this a problem with my vision or with the sight on the pistol? What's the proper method of re-aligning a sight on a pistol? Should I move the rear sight, or front sight? If I want to move a grouping of shots from left to center (and vice versa), what would I do? Are there diagrams that explain the process of realigning sights on a pistol?

thanks in advance.