Place it as the payoff at the end of a scene, once the prediction or outcome is already on screen, then follow it with Crowd Cheering to celebrate being right, or use Sad Trombone first when the doubt itself deserves a joke before the answer.
Über diesen Sound
This is a short two-second voice clip built around the words 'I know so', delivered in a firm, matter-of-fact tone that leaves little room for argument. It lands as a confident, slightly smug comeback, the kind of reply that shuts down a doubt without raising its voice, and it works best when the answer was obvious all along.