In general, when I want to correct someone's understanding I frame it as a failure of my own understanding. Like, hey, I'm the asshole here, would you do me a favor by going over this one more time for me? This is great because it allows the other person to graciously concede your point, and to feel like they're the one helping you. It's also great because when it turns out you're wrong, you don't have to backtrack.
Additionally I find it useful as an exercise in suspending belief. Sure, I think I'm right, but let's set that belief aside for a moment and explore our understanding. Nothing misleads people more than the conviction that they're right.