Editorial syncs with a single folder in your Dropbox account, and you can edit all files within that folder. It is possible to use the root folder of your Dropbox as the sync folder, which makes all files in your account accessible in Editorial. As an optimization (because syncing all your files could potentially be very slow), Editorial only syncs subfolders that you've opened at least once in the app though. I hope that clarifies things a little bit.
This is the community forum for my apps Pythonista and Editorial.
For individual support questions, you can also send an email. If you have a very short question or just want to say hello — I'm @olemoritz on Twitter.