How to display a post on a custom page

I’m creating a CMS website. (And, I’m a newbie.) I would like for my posts within the category of “about-us” to view on the About Us page.

I’ve created a custom template (about.php) for my custom page (About Us). When I go to: https://www.website.org/about-us I see my list of About Us posts there, but when I click the post link (e.g.: Our History) it views within the blog template.

Perhaps there’s something I could do within the post Custom Field area that will keep that post in About Us instead of Blog?

Any help would be greatly appreciated!