I think he means that the skyboxes are all identical, they do not reflect the exposure changes set in SE.Do you mean exposure value in the EXIF information or similar? SE doesn't write EXIF, it just saves pixels. You have to enter exposure values manually. And that values from SE are just something internal, they are not a real-world illumination or exposure compensation. So you have to adjust exposure for each layer in Photoshop/Gimp manually anyway.