Not in the theme settings no. It wasn’t how the theme was designed. The top horizontal nav menu morphs into a sidebar menu on scroll-down.
If you’re looking for simple and a sticky horizontal nav menu, you’d probably be better off looking at a theme that offers that built in.
If you’re not in a hurry to build your website, you can wait for RapidWeaver Elements stable release, as you would be able to build a sticky horizontal nav menu yourself. Check out the Dev Diary here Dev Diary Ep11 - Responsive Navigation / Q&A