Your post isn't very clear...
You hear sloshing
above the steering wheel? Like free-floating in the air above the steering wheel?
You said it only happens once you start moving if parked on an uphill slope. Are you saying that you hear sloshing when you're not moving on level ground or a downhill slope?
The clutch and brake fluids are on the other side of the firewall from the steering wheel, and I guarantee you they slosh while driving. But you'll never 'hear' them sloshing.