Section Background Image
There are some sections of the theme containing background images, so to edit it, you're supposed to edit a page with Elementor.
Scroll down to the section you need > edit the section > Style tab > Change background image
To edit the background image of the breadcrumb section, you're supposed to edit both the default layout in Settings, and layouts of templates.
Please go to WP-admin > Plazart Options > Settings > Layout > Edit the Breadcrumb section > Design settings > Change / upload background image
After changing the background image in the Settings, please move to the Templates section > edit your template > Layout > Edit Breadcrumb section > Design settings > background image
Edit Breadcrumb section in a layout
Change or upload background image