[Wendy Cutler]

On a side note, just tap the cloud icon in the file browser, then Dropbox if you want to switch to Dropbox.

Mike

Thanks, Mike. That's not just a side note. That totally solves my problem. I don't even remember now how I used to switch between a local file and the Dropbox folder. 

OK, now that I have done the backup to Dropbox, I just tested starting a backup for a local file and the option to select local file, Dropbox and two other options comes up. Perfect. 

Side note - I didn't get notified yesterday of this reply. I know I had ticked "Subscribe and receive email notification of new replies"; that's still ticked now.