Photoshop Elements :: How To Use Layers To Edit Digital Photos

I'm still having a difficult time understanding how to use layers to edit digitial photos in photoshop. Based on every tutorial I've tried, I have found a common theme: the best way to edit photos is by creating copies of the original image and making different types of edits to each copy and then merging these edited copies into one final image that reflects all the edits combined. I have been lead to believe that the reason for making copies of the original image is so that edits can be made to each individual "layer" and not to the original photo. This way the edited layers can be compared to the untouched original to make sure everything looks the way its supposed to. Here is what is frustrating me to death. No matter how many "layers" I create of my original image, every edit I make shows up in every other layer I create along with the original. I thought that any edits I make to the active layer are only supposed to show up on that layer and no where else. Is this true? If so, how do I set up my editor so that the edits I make only show up in the layer I am actually working on? It seems to me if the edits I make are going to always show up in every layer I have created, and in the orignal image, then there is no point in using layers at all when I edit my photos.