I use Photoshop Elements 15. I was trying to use the sliders under Enhance/ Adjust lighting/ shadows/highlights. I wanted to darken the lines in a drawing I had opened. I clicked on Darken Highlights and moved the slider up to 100%. I then clicked on 'OK'. the window closed and an instant later, they darkened lines had defaulted back to their original shade. Repeated attempts failed to get the setting to stick with the image. Help, please.

are you trying to apply the changes to the correct layer? I have done that when I have been tired. The other thing may be the image mode, some edits won't take to grayscale images, you have to change to RGB and desaturate if you want a monochrome image.

I think I figured out what it was. I think the image I was working with was too large. I started out with an image that was over 6000 pixels wide by about 3000 high. When I reduced it down to 2000 high by 1091, it took the change right off. So I'm thinking the original size was too big for either the program or my system to handle.