Hi, please bare with me as I'm new to photoshop...
I had a photo. Changed the background to make it white. Done my touching up and airbrushing. Now I want to add an overlay but it only appears over the subject and nowhere else in the photo/the white background?
I'm guessing you have a clipping mask, but can't tell what is happening with your screenshot. Does the "overlay" layer have an arrow pointing down and is the layer under it underlined? You can right click and choose release clipping mask.
Melissa Piccone | Adobe Certified Instructor | Adobe User Group Manager
The term "Overlay" usually refers to a Blending mode option available in the Layers panel and in the Fill drop-down field, as well where a Fill choice there (such as Color) and Overlay in the Layers panel will be affected by the tonal scale of the image leaving your image area white . Please post the Layers panel and describe the objective of the layer