On this old laptop, at 1024x768, to these old eyes, the icons shown in the topics list for each forum all look basically the same. I.e.,
- the pastel colors are hardly distinguishable from each other
- the difference between the 'new messages present' icon and the corresponding 'nothing new' icon is imperceptible.

If there are per-user settings for color, contrast, icon size, whatever, well, where do I find them?

If there are not, please review the forum's appearance on a small screen, and see if you can tweak it to be readable without your glasses, or at least without getting real close to the screen.