About Backup, normally you'd sync to somewhere, like another drive, ex: S:\Joplin or a Network drive like \MyServer\Backup\Joplin.
This way, the sync keeps a permanent backup.
I don't know if you can change in a config the local folder on Windows (which one, 7, 8.1, 10?) - but if you really want this you could use a Junction to link the local .config folder to another drive... Again, how to set it up depends the Windows version.
But IMHO the easiest is the filesystem sync - see above.