wondering

One of the factors in making your pitches really move (or in this case, sink) is to get extended out in front and get your hand on top of the ball. A lot of amateur pitchers release the ball with their hand behind the baseball and not on top of it. This causes the ball to flatten out and lose its "life" or sink. Video yourself and see how far out in front you are getting and how much you are on top of the ball. That will give you a starting point. Good luck!

When you throw the two seam try putting more preasure on one of the two fingers. More pressure on the index finger will change the path along with more pressure on the middle finger will do the same. Once you get used to the different movements you will learn what pressure causes the different movements. Hope this helps.