This is a little tricky to try to explain, but here goes. Items that are NOT hosted by an object (like a roof) can be changed from one level to another (mostly). Select the items, family catagory by family catagory. Then on the edit menu cut, then Paste Aligned/Select Levels by name. This should do the trick. Hosted Objects cannot be done that way, unless you are also doing the oject(s) that host the items you want to change the level of.