The best way, if you don’t already have it, is to get ACF 5 Pro. Us an options page and set the parent slug of the options page so that it appears below the post type you want to set values on. For example, put “Blog Options” under “Blogs”. Now you can add a field group here and use these fields on your archive pages.
Actually, I think this is the only way because WP has no admin page that’s associated with archive templates.
Before I discovered the ACF Options page add on I would create a custom post type and associate each post in the post type with one of the archive pages. This is also still an option. The main problem with using options pages for this is that the field names on each options page must be unique, so you can’t really create one field group and attach it to multiple options pages. Using a CPT eliminates the need to have multiple field groups.
