TKY SUper 8 plugin - problem lowering the amount of dust

Hi there. I've been using the excellent TKY Super 8 plugin, but on my version the Dust slider seems to have no effect on the amount of simulated dust. It is always on, no matter where the slider is set.

Has anyone else found this, and if so, is there a way around it?

For example, would I be able to tweak this setting if I had motion?

I'm quite new to this so sorry if my questions seem basic!

Thanks
Simon