Hello Zimith

You can use the Change Properties function (the icone should be on the left of your screen). Click on it, select your structures and right click - "do it"

Then you tick the box in front of Layer and you select "Structures" in the drop menu, then OK.

It may be easier to select your symbols if you hide all sheets except the "Symbol" one(s).

That is how I would do, but I am quite the beginner with CC3 myself. Others here are more experienced and may have faster / less tedious tricks.