I love yarny. Truly I do.
For those who are unaware, yarny.me is a cloud writing program featuring "snippets" and "groups"; snippets being, essentially, sections of story (you can make them chapters, parts, pieces as you see fit) and groups are what they sound like: groups of snippets. It also has a sidebar where you can save character information, location, and just about anything else.
Unfortunately, it is also a cloud writing program. Which means that you need internet to use it. Although, for the most part, that is a good thing, there are places where I like to work that simply do not have any kind of connection.
My solution: back up my work on my computer. In this case, I use Writer's Cafe. It's a great all-in-one writing program with a simple interface that, essentially, serves as an alternate desktop which includes a storyline program, journals, ways to keep track of information, tips on writing, quotes, etc.
Essentially: keep everything backed up in a way that you will always have access. Sometimes you don't have internet. Sometimes you don't even have a computer. Just make sure you have it.