I have the Executive series phone. I have 2 separate lines plugged into each of the ports on the back. One is labelled Line 1+2 the other Line 3+4. When I have an incoming call from the line that is plugged into Line 1+2. Lines 1 & 4 Light up. When I receive a call from the line that is plugged into Lines 3&4. How do I dedicate specific lines to each of my 2 numbers?