Normally I have no problem overriding CSS codes, usually in the Customizer on the front end. I've been trying to modify the .wpforo-last-post-author item so that it is not red, and the a.wpf-new-button so that it is not orange. Using the inspector I find these can be edited in the inspector but when I copy-paste into the customizer, they are not working. I do not see these options available in the back end Forum colors and styles panel. 

I even downloaded a colors.css file to see if it was there, but is not. Is this located elsewhere in the large amount of settings panels?