How to use defaultBackgroundImage in content - articles, lists, not connected to homepage?

[tetricky]

Thank you very much for blowfish, and blowfish-tools. I am far from an expert with web development, but this makes a very satisfactory platform extremely accessible.

I am not well versed in Hugo either...I'm increasing my experience through exposure via blowfish. This is likely to be a stupid question. My apologies.

I have a defaultBackgroundImage set globally, along with a homepageImage set in [homepage] with layout set to background This works well for the homepage.

I have content, that is not listed on the homepage, but rather accessible by menu's (all working well). I would like to have the background image displayed as the default background in other content. The structure and addition of new posts to these menu lists work perfectly.

I cannot seem, whatever settings I have tried globally, to get any form of background image displaying on any of these posts within menus (not directly linked to the homepage).

Am I using blowfish wrongly, or overlooking something simple? Is there a way to achieve what I am looking to do?

I'm building this in a local environment using blowfish-tools (and manually), also using github actions to build for gh pages, and a static hosting environment (pushed to from either a local build, or gh actions). I'm getting consistent behaviour whatever the backend.