I need some help with hiding npcs from players

I have been informed by my players that when they are using the text box, the bit underneath where it says "as:" where the dropdown menu is reveals every single npc and monster i have for the camapign. i have gone onto the monster/npc (each one had to be done separatly) information on the journal tab and set it to myself only but they can still see them. What do i do to stop them from being able to see this?

They should not see them unless you have assigned control to the players.  As a note: the DM does not need to assign control to themselves.  I suggest using a dummy account, logging in to the game with that and see what the dummy account can see.  If that doesn't help please supply screenshots   of the journal tab  from the dummy account and the DM account.