Hello again, OTH,
this option is available only is some of our themes.
The screenshot you have taken is from the Emporium theme. And if you are using that one, in particular, you can change the SOTD background image from the admin panel -> Nop-templates -> Themes -> Emporium -> Settings -> Additional settings -> Sale Of the Day Background Image
Hope this was helpful.
thank you for reporting this. We fixed the filter functionality and released an update of the theme. If you update the following file you will not be having this issue anymore:
Hope this was helpful!