That's not really a preview it's just showing each layer. Nothing wrong with that.
Also it's showing the boxes because you have told it to be transparent.
When you go to create a new file in the option "background contents" select "white" or "background colour" instead of transparent.
Also it's showing the boxes because you have told it to be transparent.
When you go to create a new file in the option "background contents" select "white" or "background colour" instead of transparent.