Hello,

You can change the “Page title size” to “Small” via Theme Settings -> Page title and the font size also will be smaller.
https://gyazo.com/8b5d2de0547bb412abcf041a0b4fa4b0

02.Add below Custom CSS code to Theme Settings > Custom CSS > Global custom css:

 .wd-back-btn.wd-style-icon>a {
      display: none;
}

03. There are two kinds of breadcrumbs in our theme: one comes from WooCommerce plugin and one from WoodMart. If you want to customize our theme’s one, you need to edit the file inc/template-tags.php.
As for the WooCommerce, you can try the solution from this article https://kb.yoast.com/kb/add-theme-support-for-yoast-seo-breadcrumbs/

Best Regards.