I leveled up my dragon disciple, but I didn't see anywhere in the menus to select the color/elemental immunity. I wasn't sure if there was some kind of command to do this or if it would default to Red since that was what I was before (maybe only approved for red?) - but I don't have fire immunity, so that doesn't appear to be the case. I checked my feats and I don't have any elemental immunities listed.
Also, when you equip a weapon, the attacks on the character sheet still show for the bite/claw attacks. The damage below reflects the properties of the weapon equipped.