select layer to select all items within to change them individually.

I used to select all items within a layer by clicking on the layer itself, and then change line style etc, but now when I do this it changes the layer style which looks the same but of course the colour etc. of each individual line has not changed. I have not changed the way I do anything so I am sure that there must have been a change in the way Illustrator acts in response to my actions. Is there a way to go back to only changing layer attributes when going into the attributes panel instead? I often work in a different colour on a new layer to clearly see my work and there are other reasons I may want to change the attributes of all the individual elements within a layer and the way I used to do it was so simple and quick.

Thank you.