For some reason when I use the adjustment brush when selecting a colour to remain
How are you selecting this color to remain? Explain in detail how you are selecting this, or show us a screen capture indicating where you are setting this color.
"....when brushing over an area it isn't turning red as it was before."
Have you tried pressing on the O (for Overlay) key? What are the Flow and Density settings?
I followed a tutorial on how to highlight colour and initially it worked by selecting the adjustment brush and putting the saturation to -100 so when moving the brush where I required it showed where I had painted in red. Now however it doesn't show anything when I paint over so I can't see what I am highlighting. Settings are the same.
This is the first time on this forum and I can't see how to add a screenshot to this post.
Hello, to add a screen shot all you need to do is press 'Print Screen' or equivalent on a Mac and then in an Add Reply window on the forum press Ctrl-V or Command-V on a Mac
Definitely, you have to press letter O to turn on this overlay.