The Cura Filament Cooling Fan settings are on the Advanced Tab at the bottom - Cool - Enable Cooling Fan
Your only choices there are -
Fan on at Full Height
This is your Z height where your fan will be turned on to its minimum
percentage setting. Especially helpful with high temperature retaining
filaments such as PLA. This will be scaled between 0%, and your minimum
fan speed based upon layer height; with it being disabled for the first layer.
Fan Speed Min
This will be the speed your fan runs when enabled at full height. Once the
Z height is reached for Fan on at Full Height, this will be the speed your
fan runs at.
Fan Speed Max
This is the fastest speed at which your fan will ever run. When your print
speed is slowed down due to minimal layer time, your fan will run between
minimum and maximum speed. The maximum fan speed is reached when
your printer must be slowed by 50% or greater.
The other fan (center) cools the extruder throat. This part needs to remain as cool as possible - heat creep is the enemy here.
The center, throat fan should be on full all the time. Cura provides no way to adjust this. You want it on.