what do you mean so all 4 bulbs stay on? so all 4 are on with the regular running lights, or they all blink with a turn signal? i have mine wired so all 4 are on with the headlights. let us know which you're trying to do and i can help
you have to get a new socket for the top lights (so instead of the 2 wire socket, you have a 3 wire socket like the bottom bulbs have), i had to get new taillight wiring harnesses for both sides for mine to be able to do this. basically you're just transferring the turn signal wire and ground wire to the 3 wire socket and just tag the last wire off the running light wire off the bottom socket, and then put a 3157 bulb in the top instead of the 3156 bulb. sorry i don't have the wire colors for you, i'll check what they are a little later today
I did a different setup. I didn't like that the running light/brake light was on the bottom. Without cutting and splicing wires I decided to cut the rings and swap. I used a hot knife to cut then plastic welded them back. See my photos. The first photo you can see the completed one on the left and the higher looks way better! Last picture shows two xterra's side by side to display difference. No longer look like a low rider at night!