Charge in simple circuit

HI, in a simple circuit, Q=nqA.

I wanna ask that wt is kept unchanged in any points of the circuit? is it Q , or nq ?

my teacher today said that nq is constant throughout a simple circuit, so that higher the cross section of the wire, lower the velocity ( I =nqAv)

if it is true, that means in a non - uniform cross section circuit wire, the Q at any point of the circuit is not the same ?

thanks