If you know a little bit of coding, I might be able to help point you in the right direction.
I don’t know off the top of my head but it might either be editing the CSS of your Discourse forum or editing the HTML/PHP that gets sent from Wordpress to Discourse (I assume you’re using the Discourse plugin on WP), or both.
Could you share links to your WP site and your discourse forum here (or privately in a message to me) so I can take a look to see what’s happening?