Video shifts color temperature in the middle of shooting

A lot of times when I am shooting video the color temperature will swing wildly from warm to cool if say a hand enters the frame. It’s incredibly frustrating because it basically ruins the footage. I’m sure this is auto white balance but why would it change in the middle of rolling? The only thing I’ve learned is to set the focus, then the color temperature will stay. However there are a lot of instances where I want the focus to follow something so that doesn’t always work. Is there a way to stop the temperature from shifting in the middle of footage? A setting perhaps? It’s so frustrating to shoot something beautiful only to look at it later and see it’s ruined because of the color temperature shift.