Microphone Troubles

There are three of us in the chat, lets say Daisy, Grant and myself. I can hear Daisy and Grant just fine. Daisy can hear Grant and myself just fine. Grant cannot hear Daisy. Last week, Daisy could not hear Grant. All of us are familiar with computers and we tweaked every button we could find. What are we overlooking?

Are you guys using audio only or are you enabling your webcams as well?