If a backup is stopped, it seems that it gets resumed on whatever settings it previously had, regardless that you’ve reconfigured.
Perhaps a button for stop & one for “Stop and discard.”
Consequently it seems I must wait while a 17GB backup completes with errors, even though the RECONFIGURED settings mean a much more reasonable ~350MB
I know I could run remove unknown or cleanup, but that would also interrupt running image backups & cause them to start over too, & those are huge, been running over 24 hours & similar still till completion, so I don’t like that option right now.