Hope you are well.
1. You can change the background image in Theme Options > Breadcrumbs.
2. You can also change the background image in the page meta box when your site is not full site editing(fse) mode.
3. You can also change the breadcrumbs section using the block in the Porto template builder.
– Create a block in the Porto Template Builder
– And set conditions in the “banner” of Porto Page Layouts.