How to get cateegories to display as home page.

I’m trying to work out how to get the category pages to display mosaic as the homepage does.

I have seen the other topic, but the answers aren’t clear to me.

I have pages, that link to the categories via ‘page links to’

When I go on the categories in admin area there isn’t an option to change the theme template. When I do it on the pages that link to the categories, it makes no difference (which I didn’t think it would)

I’m using the pro version.

I really need an idiot’s guide.