Adding a feature image to the top of the posts page

I’m using a theme that allows the user to display image banners at the top of each page below the header.

I’m running into a situation where the posts page is not the front page, but a page called Work Outs. When I set Work Outs to display the posts, the top image that was set with the custom field option is being overridden.

I tried creating a custom template that would display posts, but the code I found only displayed 3 posts, did not allow for going to a next page of posts, and the post title was no longer a link.

What I need to know is if there’s a way to set a top banner or feature image above the posts on the posts page, or a better way to display all posts on a custom page.

I’m sorry but I cannot share the link as it’s an unlaunched site for a client.