how to increase the sensitivity of sound sensor

Hi, i have two sound sensor boards, both don't work very well. I even placed those near the speaker playing heavy metal, but they gives me the analog readings no more than 50. I have to blow directly at the mic of the modules to get the reading larger than 100. But no matter how I hard I blow, the reading is no larger than 600. And they definitely not quite response to my clapping. So I wonder is there any way to increase the sensitivity of sound sensor? I already did turn the potentiometer all the way anti clockwise to get those readings.

Thank you!

Datasheet please...

Basically you can't without soldering in new surface mount resistors. Are you up for that?

Before you do are you sure you have wired it up correctly?