I have workflow instances that were initiated on a particular date that keep sending 'Workflow has errored' notifications to initiators and Admins. I have disabled the setting on CA to stop error messages from being sent to users. This however has not solved my problem. Does this mean the changes will only apply to new instances and not workflows that are already running?

NB: When I check the affected workflows, I don't see any errors, either the workflow has completed successfully or still in progress.