OneDrive permissions sharing

hi - I'm looking for help in setting up a folder and subfolder with correct permissions.

The desired outcome - a general folder I share with operations, and a more restricted folder I share with operations directors.

I tried have granting access to a wider audience with a top folder, and then granting access to directors in a subfolder.
However this didn't seem to work - the general access cascaded down to the subfolder.

If folder permission rules cascade down to subfolders, do I need to create them separately - i.e. one folder for operations, one for operations directors?

thanks
James