Dynamic Lighting Problem: Making the unsearched parts of the map black instead of a grey screen.

I am trying to put dynamic lighting to one of my maps for my campaign. I followed the tutorial instructions for dynamic lighting (easy to understand video!) and entered as a player. While the parts I blocked were greyed out, from my POV I could still see all of the parts of the dungeon. I will share the link but I feel like I'm missing something. Any help would be MUCH appreciated.

It sounds like you have Explorer Mode turned on. If Explorer Mode is turned on, then each token retains a ‘memory’ of the map that has been explored but is no longer visible.  I also strongly suggest using a Dummy Account instead of ‘Rejoin as Player’ or Ctrl-L. 

You can reset the explorable darkness on the toolbar in the eyeball section: I second adding a dummy account.  You can join from another Chrome profile, a different browser, or incognito mode so that it doesn't mess with your regular login.