None of your examples would make me think you would be a “know it all” by responding to such idiotic opinions. That would depend on how you challenged the dumb thing they just said

"Oh? Why’s that? " (Said genuinely asking why they hold that opinion) is a perfectly fine response to that kind of idiocy.

Though perhaps we have her different ideas of what a know it all is. “Mansplaining” to me is iconic know it all behavior