FQ stands for frequency, Q stands for bandwidth affected. Its a parametric eq. Search it here, or google it, tons of info to get you up to speed on how to adjust a parametric eq correctly.
Parametrics are generally not intended for a laymen to use. You should definitely spend the 15-30 mins it will take to research the basic functions of it before you try to use it to improve anything.
No eq will fix a blown mid, which it sounds like you have. Voice coil rub.