How to store and manage singular data in Rails?

I'm developing a site with Ruby on Rails. I have data on layout that doesn't repeat more then once. And I need to enable content-menegers to change it easily. I could create a model or several models for them and let content-managers edit it in RailsAdmin. But I doubt I should use models that way because entities of such models will be ment to exist in singular number. I mean there aren't multple site names, logos, backgrounds, welcoming texts, etc. But I want to enable them to be edited in a web-interface or equally comfortable not worrying about the cache and not looking at code and serfing through complicated directories structure.

What is the right way to do that?