I am using multiple LEDs (20mA 3-12V) in parallel to indicate active circuits in a car. They are too bright at night, so I put a 250K potentiometer to their collective ground. At less resistance, some LEDs are brighter than others. At greater resistance, the brightest LEDs become the dimmest. 1. How do I make them respond equally? 2. Will they eventually burn out when set at least resistance at the pot? 3. Why is this happening?