Editing with Layers

[debc]

I am having problems using layers while editing a photo. I am using PSE 9 on a MacBook Pro running Yosemite.

For instance, I am editing a photo of my Mom and Dad, using the spot healing brush on their faces and whitening Mom's teeth. These are my layers:
Pearly White 1 (Mask)
Mom's Teeth
Dad's Face
Mom's Face
Background

OK, now I think I am finished......but......I see something else I want to fix on Mom's face. When I click on that layer, it won't let me fix anything now. How can I fix something on that layer now? I have never been able to figure it out and I know there must be a way.

Thanks for your help!
Deb

 

[GingerScraps]

I actually do not know, sorry wish I could help

Maybe try searching YouTube, I usually have luck there when I can't figure something out in Photoshop.