How to Develope and Use a Two-Seamer (and Change)

I’m really interested in developing my two-seamer. While most kids my age are trying to throw curveballs and (gasp) knuckleballs, I’m really working on my circle-change and two-seamer. Here’s the lowdown on my pitches:

Two-seamer: I get really cool movement on this. It sinks and runs in (I’m a righty). However, I don’t know what arm slot to throw it to get it consistent or how to pronate when I throw. I have a habit of throwing this low because I think when I throw it when I lower my arm slot. Inconsistent control.

Circle-change: I actually have to throw this kind-of hard just to get it over the plate, but it is definitely slower than my fastball. I really don’t get trailing movement and I guess it sinks a little. Again my control is inconsitent.

Can someone help me with these two pitches?

well with the 2 seam their is no pronation. its all in the grip. I think it moves most with a high 3/4 arm slott

with the change try to use as much arm speed as the FB and again all in the grip