I am running vMix basic on a Dell laptop, running Windows 10 Home with two PTZ Optics PT30X-GY-G2 cameras connected via network connections on static IPs.

When the church begins livestreaming mass, they say that there is an audio delay when hearing the mass in person and on the speakers of the laptop.

What setting do I need to change to change the delay?

All digital audio and video devices have some inherent delay. The conversion process from the camera sensor or audio source to a digital data stream takes time.

There is also a tiny bit of delay added by vMix processing / mixing sources and overlays.

Finally, there can be significant encoding delay converting the vMix program feed to whatever format you are sending out to the world (stream, local NDI, direct vis SDI, etc.)

The only way to deliver near real time video these days would be a camera SDI/HDMI feed straight to a monitor.