audio issues

Hi, I am using two Yamaha monitors so I can hear shared computer sound (playlists) for my zoom yoga classes. I connect the monitors to an interface and the interface is connected to zoom on my MacBook. What can I do for the fact that I can barely hear the music/monitors. It could be that I need to download the interface software to control volume. In my sound settings preferences on my mac and while on zoom and with audio connected, the window says there is no output controls for the speaker volume. Maybe I have answered my own question but if possible I would like to avoid downloading yet MORE software to boggle my brain!!🤔 🤔

Anahaat