Not sure about your phone. Mine was definitely not in tws plus mode. Its showing the connected one as master. As in this case the right earbud. And for switching, can just disconnect the right bud from this menu and tap the left bud to connect as master. For tws plus to work, phobe have to support. And using qualcomm soc. Unless samsung is able to provide tws plus function with a firmware update, which i highly doubt so.
I think the disconnect happens when the master earbud is being put back into the case?