Raise the hood, look inward and you'll see a plastic retaining lock (hook) tensioned by a metal spring. You pull on that off its retainer. Pull out the signal assembly off the fender. Replace the bulb by twisting out.
Ok the issue you have is that the comfort module lost its programming that why it only opens the drivers door with the remote to reprogram this feature you will need a vw specific scan tool to change the coding in the value blocks you will need to find a vw service shop to be able to do this for you . I hope this helps. ---Mine did this when the bat. went dead---Read more: Volkswagen Passat GL 2004 passat only drivers door will unlock - JustAnswer http://www.justanswer.com/vw-volkswagen/4emry-volkswagen-passat-gl-2004-passat-only-drivers-door-will-unlock.html#ixzz1eVaGFaCd