First off it should be noted that archive, category and taxonomy pages are not ordinary pages that you can edit and customize, but archive-type pages.
Archive-type pages, sometimes referred to as taxonomies, are rendered dynamically according to your content. For instance if you have 10 items in a category, each and every one of them will be displayed on the page. If you have no items in that specific category, there’s simply nothing to display.
What all this means is that archive pages are WordPress' default way of grouping posts and custom post types according to certain tags or categories.
It’s also worth mentioning that these pages sometimes aren't affected by the general Theme Options configuration and you have to style the content of these pages manually – and by this we mean via Custom CSS.
It's important to stress out that the PHP template for these pages is written in the core theme files and can't be changed by default.