Roof is leaking. D:

Hey all, I have the fan vent that everyone seems to have (fan-tastic vent I think it's called) but no matter how much silicone my buddy and I throw at it, we can't seem to get it to stop leaking. Does anyone know of a better way to fix the problem? Any good videos to take a look at? Thanks!

Also, I have noticed a bit of mold already forming so if you have any tips for taking care of that I'm all ears as well.