Shortcode styling not working

I bought the plugin because I want to create a review page with all reviews on one site. I use the shortcode to display them, but most of the options (background color, text color etc) do not change.

1.) What is the problem with the shortcode and how can I make the plugin work?

2.) I do not need the black speech bubbles. How can I delete them in the shortcode?

3.) How can I change the “verified customer” icon? Only with CSS? Were do i need to place it?

Thanks for your help!