Site not responsive.

I have the Catch Evolution latest version. I just performed a "Google Mobile-Friendly Test" and it failed. I have examined every aspect in the >>Appearance>>Customize>> I am not able to locate anything that would appear to make the site responsive. Can you suggest something that I can do to make the site responsive for mobile devices. I also verified on my Android phone that the site looks rather jumbled and not mobile-friendly. Thanks!