Ok, everyone wants a ring that collides eachother, Like the Theia crashed into Earth and made particles around Earth, right? Ok, here is it. If you dont like it, do this method:
1: Load "Earth and Moon"
2: Set the object to 6000-7000 km.
3: Shoot at the Earth
4. Pause
5. Delete the moon (if you want too)
6. Put the velocity rate 10-15 km.
7. Put the explosion rate 200 ( 100 if you have slow computer )
8. Play
9: Click the "Explode" button.
10. Wait for five secs
11: Click "Orbit All"
Ok, watch them crumble into large moons.
Picture is the moon is about to form.