Hello wfm-admin. Thanks for reaching out to us.
Closing FileManager would indeed stop the sync tasks from running, but there should be no reason for the task to run outside of your schedule; unless perhaps you have another machine setup with a similar synchronization? Please first make sure that you do not have FileManager syncing on another machine. Next, please try re-installing the newest version of FileManager from our software page (this will not remove your sync tasks).
If you are still having issues after reinstalling, please reach out to us via email at email@example.com so that we can help you a bit more comprehensively. Since we are dealing with computer-specific issues, connecting remotely might be a necessity.
Look forward to hearing back from you.