IF you are going to use super glue, only use the gel kind. Pure cyanoacrylate gel.
If you want to go another route, there's aquarium safe epoxy putty, which is a little more permanent.
Another way to do it is to rubber band them to a rock.
Yet even another way is to use some fishing line to tie them to a rock.
I like to use toothpicks on some corals like xenia to hold them into place.
You can attach those little squares to wherever you like in the aquarium, heck even the back glass if you want. It's your tank! lol.