Backup adds to file icons a blue box with 2 facing arrows - how to delete?

Hello! After a Norton back up I got all files in all folders in Windows Explorer tagged on the icon left corner with a blue box and two facing arrows. I want to remove as quite annoying (e.g. see icon image attached). From several forums discussions I understand this might happen at the moment of back up and i needed to change Norton setting. However, I deleted the back up and changed Norton setting by unchecking both the "backup" and "backup status overlay" but the problem still remain. Can you please help?

Thank you