ahh, yes you are really confused Hope this gives you an “aha moment”.
This has absolutely nothing to do with what you see in a browser. Forget about that, it’s irrelevant. You can’t make changes in a browser and expect them to show up in Rapidweaver. Rapidweaver project files live on your computer and have no way of getting changes you make in a browser. Any styling changes (or anything at all relating to your website) needs to be done in RW, with the theme settings. Then, when you publish, you will see changes.
Not sure how your theme works and the options available. You might need a different theme. The right part of your screenshots is showing the theme settings. When you are saving those settings, it ONLY relates to those options you see. For example, if you change the color of the navigation link to a red, then save your style, you will see changes. or, change the font family from Ubuntu to something else listed in the drop down. etc. Then when you save styles, it will show up on the page.
and yes, as @thang said, reading the manual or watching tutorials is a MUST