MoPhoto Detroit

I am having a horrible time transition from still photography using a DSLR to filming with one. The problem is focus. Let’s say I’m filming an interview between two people. They are seated behind a table on roughly the same plane. I focus on one or the other and use f/13. Plenty of depth of field, right? And yet if one or the other begins gesturing or talking with their hands it throws my camera into a focus finding dilemma. It struggles with focus and makes noise while doing it. Anyone have solutions or suggestions.