It is a well-kept belief, among true Mormons, that the God they believe in, is only God of this planet and its immediate areas. This is held to because Mormon doctrine teaches that humans can eventually become gods themselves and be granted planets to rule.
In Doctrine and Covenants 132:20 it says:
Then shall they [faithful Mormons] be gods, because they have no end; therefore shall they be from everlasting o everlasting, because they continue; then shall they be above all, because all things are subject unto them. Then shall they be gods, because they have all power, and the angels are subject unto them.
If a faithful Mormon can become a god, then they have all the privileges of a god, including ruling planets, and controlling people. Because Mormons teach that God was once a man, and that He rose the “steps of godhood”, that man can do it to.