Changing the resistor to be in front or behind an LED doesn't affect brightness?
Switching the positions of the LED and resistor will have no effect on the brightness of the LED because they would still be in series.  The current through them would be exactly the same.  Thus the brightness of the LED would be the same.  The voltage drops across the resistor and the LED would be the same since the current through them is the same.  This is a characteristic of all series circuits.