Why the assumption that whatever formed it is unconscious? Isn’t it equally possible that whatever formed the universe could have been conscious or unconscious?
I don't think so. As far as I can tell, consciousness is something that happens in complex structures like brains. I find it very unlikely that such complexity was around in the early universe.
Also, I prefer 'non-conscious' as opposed to 'un-conscious' as the latter implies there is a possibility of consciousness. An atom is not conscious in any sense I can see.
How do you know that it isn’t you that’s forming the universe in your own consciousness?
If the universe is internal to me, then there is nothing else to do. I assume there is something outside of myself as part of my study of my sensory experiences. And that assumption has made it more possible to predict future experiences correctly.
Solipsism just isn't an interesting philosophical position in my view.