Hey, thanks for taking your time & for installing our plugin, but we kinda get the feeling you haven't explored the full potential of it. And we would love to help you out!
The thing is, you don't have to go and edit every & each of your already published blog posts to add related posts in them — it is already done automatically, by our plugin, just after you install & activate it.
What you are referring to is probably the widget with related articles from around the web, that loads up just below your editor.
But that one is meant for your future posts, where you can add those related articles directly into the body of your blog posts, and thus offer your readers even more quality, related content from around the web, alongside your own related posts. (Here's an example blog post from one of our users.)
So to sum it up: your own related posts are inserted automatically, no matter what, but the ones from around the web you will have to add manually, since you're the only one who has to have control of content that's not your own, in order to avoid any blackhat problems that might occur with Google later on.
Hope this makes more sense now, but please do let me know if you had something else in mind or if there's anything else that I could help you with, since I'll do it gladly! I'd love to hear your thoughts!
Take care & I'm looking forward to your reply!