EQ setting just refers to the levels of the adjustments they have such as the low setting (men’s voices and thump type sounds) and high setting (kids voices, hisses, screeches, shrill things). My comment then just means they (and/or you) may have to experiment with the adjustments available to find one you like. It would be great if they could do that while talking to you on the phone because then you could hear the changes almost instantly.
The term itself comes from:
“Equalization, or EQ for short, means boosting or reducing (attenuating) the levels of different frequencies in a signal. The most basic type of equalization familiar to most people is the treble/bass control on home audio equipment. The treble control adjusts high frequencies, the bass control adjusts low frequencies.”