Admittedly the red ones on the forum list are very subtle. These are the default ones and I will get them changed to the yelllow. Changing all of those icons so they are more clear is on the todo list.
If you mean highlighting new posts within a thread itself, not sure how to do that and would have to look into it.
Other forums on the same board as this have a single button titled "new posts". Click that and a full list of new posts in all threads appears. I can't see how to upload an image without having my own website so my description might not be the best.
Edit, Imgur is my friend.
Here you can see a single button that will bring up all new posts. Saves trawling back and forth to the main index and looking at individual threads.
I'm far from a geek and have no idea how it is done. It may not be possible on here.