I had the same problem not to long ago. See if this works for you.. If you have a mac, hold down the option key while choosing the adjustment layer (I used curves to lighten) and when the dialog window pops up click on "use Previous layer to Create Clipping Mask". When finished, dup the adjustment layer and move it above the other layer you want to adjust. Hold down your option key and click on the line between the adjustment layer and that layer. Repeat as needed. I'm sure there are other ways to do the same thing. Hope this helps.
~Nancy~
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