Thank you @webrunner5 that is very helpful. After posting the above I discovered that the a6400 has a toggle to lock the AWB. So it looks like I can go to, say, the high school gym, allow the camera to find the correct white balance automatically, and then hit the toggle to lock it; that way it will stay the same as I film the competition and I won't have to worry about it. Seems like a really cool feature. In the Venice style there is a white balance adjustment for both A-B and G-M. I don't know how important those are but I guess I can test it out.