As an Indian in the US, I do not understand what is acceptable, and what is not.

Eg: An elderly woman was sharing Uber pool with me. She was complaining to someone over the phone about how Uber's new app does not have an option. I knew that the option was present, just that they moved it to a different page in the app. Should I communicate this to her after her phone call? What if she thinks I'm listening to her private conversation? I finally didn't tell her anything.