This article is deprecated starting with QOwnNotes version 1.2.8, since note folders are now fully configurable with their paths on your ownCloud server.
To understand why the QOwnNotes settings are reporting a problem with the ownCloud path you first have to understand why QOwnNotes needs your main ownCloud sync folder.
For QOwnNotes to be able to properly communicate with your ownCloud server to check your note versions and the trash it needs to know where on your server your notes are stored.
When you first have started QOwnNotes you have selected your notes folder, by default that was:
In your settings dialog you normally would set as your main ownCloud sync folder:
This is the folder where you have setup your sync folder in you ownCloud sync client.
Now QOwnNotes can determine where your notes are stored on your ownCloud server (it would be "/Notes" on your server) and tell ownCloud where to look for note versions and the trash items.
You can use different note folders in QOwnNotes by setting new note folders, and everything will be all right as long as your note folders are all in your main ownCloud sync folder.
You can switch back and forth between your note folder with the menu entry Recent notes folders in the Note menu.