How do I get lightmap to use a different UVW channel?

I am having issues with black dots appearing on some models. I have tried overriding the light map resolution to 256 and 1024 for my scenes walls. I have looked into the UVW on these models and for some reason I have three separate channels? Could someone please explain how I have three and how to get the lighting to use my channel (0) instead of an automatically generated one (1). See pictures attatched.

Many thanks to anyone willing to take time out of their day to reply to a struggling student.

I have changed the lightmap coordinate index to 0 and built the lighting but the issue persists.

FIXED

Went back to 3dsmax and made my own second UWV channel with lots of space between islands and scaled the front so it got more lighting detail