5.1 surround sound I installed the home theatre system - but I dont think the audio setup is

Question

I installed the home theatre system - but I dont think the audio setup is correct. When I play music it seems to lack bass... very much.... It has the option where I can adjust each speaker (front left; front right; centre; subwoofer etc) with the distance and decibels volume -6 to 6 db... What should it be?