How Change folder Access?

[Photon]

F2-210, TOS ver 4.2.28

When I originally set up this NAS, I gave my user account administrator permissions: full read/write. I created a share "Backup_Files_Vol2," and I created a subdirectory "TV_Shows." I then copied a bunch of recordings to "TV_Shows." Now that I've read about how defend my NAS from malware, I'm trying to change my user account to have Read Only access to this and most other subdirectories on two volumes. Using File Manager (while logged in as Admin) I've gone to "Backup_Files_Vol2," and I changed permissions for my user account to Read Only. I also ticked the box for "Inherit permissions to all subdirectories." I clicked "Confirm" and received the "Operation Successful" reply. However, the "TV_Shows" subdirectory still shows I have Read/Write access.

Is this because my user account name is the owner of this subdirectory as show on the TV_Shows>More>Property>Information tab? If so, how do I change the permissions for my username to Read Only?