Locating the face at point
Enter the beautiful self-documenting nature of Emacs. Put your cursor on the thing you want to change (remember, our whole philosophy emacs inherited from *Nix is that everything is text). Then do C-u C-x = (what-cursor-position) and you’ll get a buffer telling you more than you wanted to know about the text you’re on top of. For us, we just want to know the faces at hand; give them a search and then you’ll know just which to change in customize-face.