Mic trim controls: not sure what these do (is it a pre-pre-amp ?),

the manual says to set them so that the "mic peak" lights do not come
on. But even with the pots set at max I cannot make them light up. If
I use it with the mic trims set at max does it cost me anything ? If
I turn them down (somebody here recommended 80%), all I have to do is
turn up the recording level controls to get the same signal strength.
Does it all amount to the same thing or is there a multiplicative
effect here that is not obvious to me ?