This feature is still in the backlog.
-WarrenMarc Prosch commented
New to Teams, and we have realized this was not a changeable. I am astounded. Why would the conversations tab be a forced default. Teams is supposed to be a simplified interface and I have had 3 complaints from non-tech savvy employees about this now. We aren't really going to use the conversation tab so my users are required to add an unnecessary click for each team they are involved in.
Please reconsider the backlog you put on this....... ALMOST 2 YEARS AGO.