Hi wima,
First of all, I’m really sorry have taken long time to reply you.
1. Go to Theme Settings > Styles and colors > Styles and enable Dark theme
option https://prnt.sc/qjbJ7p5XsH7I
You are using a Custom Single Product layout, which is built with WoodMart WooCommerce builder. Navigate to Layouts > Layout to edit Single product layouts > and remove Background color
from Container
widget https://prnt.sc/zJVOGriwWocq
Further, you can read more about the Layout Builder here: https://xtemos.com/docs-topic/woodmart-woocommerce-layout-builder/
2. You can do it with our Theme Presets feature.
Then you can use Condition to select page you want to background image > then click on Edit theme settings https://prnt.sc/aYNAEYxVQFU9
Here is our documentation on how to use theme presets. https://xtemos.com/docs-topic/theme-settings-presets/
Regards,