This parameter controls the complexity of the plasma. High values give a hard feeling to the cloud (like an abstract oil painting or mineral grains), low values produce a softer cloud (like steam, mist or smoke). The range is 0.0 to 7.0.

This option controls the randomization element. The New Seed will generate a new seed. There is no reason to use anything else unless you want to be able to repeat the exact same pattern of randomization on a later occasion.