Ok, sounds like you disabled it properly then.
One more thing to try that seems to help with NS problems: Click on mailbox to cycle through all the outstanding notifications (might take a bunch of clicks but you only have to do this once, we hope) until you get the "Nothing new has happened recently" message. Then set your desired NS settings, save game, exit and re-enter game.
If that doesn't help then there is a thread here about a persistent bug which does seem to happen to some people, unfortunately, but you could leave a Me Too and/or share your info.
https://answers.ea.com/t5/Bug-Reports/OPEN-Can-t-disable-Neighbourhood-Stories/m-p/11365891