I changed the scene viewport to dark but when I select faces it is difficult to tell which ones are selected, is there a setting to make them pop out more and/or change the color?

Moin,

open your Houdini installation directory, go into the houdini/config subfolder. There you find a few “3DSceneColors” files with endings like “dark” etc. Open the one you are currently using in a text editor and adjust colors to your likings. It's a bit fumbly but possible

Marc

thanks Marc, much appreciated.