Layers question

[NewUserJohn]

When I duplicate the background layer, and then begin working in the new layer (layers, curves, etc.), the background layer changes as well.  In other words, the two layers appear identical.  Am I doing something incorrectly?

[Chuck Uebele]

Can you show a screen shot? the background layer will also change if you have adjustment layers above it that change everything below. If you apply curves just to the copy of the background layer, then the original background layer shouldn't change.

[NewUserJohn]

I tried but ended up doing several screen shots and my reply became a bit complicated. If Windows 10 had a screen video capture utility it might be easier. Put simply, I open an image, and begin with a background layer. I right click and duplicate the layer. Then, when for example I adjust levels or curves in the duplicate layer, the same adjustments are made to the background layer. Maddening to say the least and I know its user error.

[Chuck Uebele]

Are you using an adjustment layer like the below screen shot?

Or are you applying the adjustment directly to the layer, as in the next screen shot? Are both layer thumbnails changing with the adjustment?

[NewUserJohn]

I am using an adjustment layer as reflected in your first screenshot which has exactly the effect you describe.  I pulled the curve way up to show it had no effect on the thumbnails.  I apologize for my lack of know how, but how do I make adjustments to the background copy without an adjustment layer the changes to which modify both the copy and the background?  Thank you, by the way, for the help.  It is very much appreciated.

[Chuck Uebele · Accepted solution]

There are a couple ways to make changes to just one or some layers. If you want to adjust just one layer, you can clip the adjustment layer to the layer by holding down the opt/alt key and clicking between the two layers in the layer panel - I added a layer mask so you can see the difference:

You can also put several layers in a group and change the groups blend mode to normal, or something other than pass through.

[NewUserJohn]

Thank you very very much. I'll give it a try this evening!