Hey Alvaro,
The boxes area you described is called the Ethos Post Carousel. There are a set of options available in Theme Options > Ethos. Please check them out here https://theme.co/docs/stacks#ethos-stack-settings
If there’s no Post Carousel option that meets your needs, regretfully, you’d need to override the Post Carousel PHP template. This requires a PHP developer to read and customize the template. If you’re a PHP developer or know someone who can customize the template file for you, the file you need to override is _post-carousel.php and it’s located in pro\framework\legacy\cranium\headers\views\ethos.
You can learn how to customize our themes here https://theme.co/docs/best-practices
Hope that helps and thank you for understanding.