What is your setup?
Are you using your Sanctuary sound system? assuming yes, are you connecting sound system to OBS PC as analog or digital signal. If digital, are you seeing individual channels, using a DAW, or anything similar on OBS PC? What, exactly is the audio path, and any audio effects in effect outside OBS (ie sound panel, external DAW/mixer) ???
One issue you may have is that an audio mix for in-person, is not exactly what you'll want for livestreaming (close, but there are a few tweaks for a broadcast audio signal that is often recommended, especially for users listening on really poor audio quality mobile device speakers)
- First, for singer - [just covering basics] are you sure you aren't distorting from exceeding db level?
Is pastor and singer using same mic?
- did someone set up custom filters/effect for spoken audio and those settings conflicts with singing?
for our House of Worship, priest is using a wireless lav mic, we then have identical pulpit and lectern mics, with a slightly different mix on sound panel than lav mic, and then choir has different mic/mix
I tried (not knowing what I was doing) to play with OBS's native Audio compression and other effects filters, on a brand new PC, and the audio sounded worse. But I'm told I have tin ears, so it never was a good idea for me to do the audio tweaking, and pandemic meant our sound person couldn't assist. So for now, I don't have any OBS audio effects in place. As health factors come into play during an aerosol spread pandemic and singing, all of our music is pre-recorded (as are readings, prelude/postlude, announcements, etc), and only priest is live (though recently, prayers of the people/lecter has been another person, now that we have PTZ camera and can use broader alter area).
so solution approach likely to vary depending on whether you are doing in-person worship or not, and assuming Sanctuary sound system, what the in-house mix is like