Layer problem

After appending items into a scene all layers show as being in use. How do I clear the unused layers so that only used ones show.



To clear a layer , you need to move every objects in it into another layer or simply delete them all.
If you mean all the layers are currently highlighted as being all selected at the same time, just click on the layer you want to use, the other ones will be automatically deselected.

I have 7 layers in use and when I append an object from another file all 20 show as being in use. Why does this happen when the appended item was in layer 3 in the appended file. I have managed to move the items now.