If you are crossing your foot step over into the midline of your body, you are probably over striding and landing on the outside of your foot.
So focus on taking shorter steps AND striking the ground using your entire forefoot, not just the outside of the foot. Think about engaging and using your big toe.
One way to feel and practice this is to simply run in place, barefoot. Notice how you naturally strike the ground under you, with a "full" forefoot strike.
Hope this helps and stay patient. This will take time to change.