This feature is still in the backlog.
-WarrenJames Chumas commented
I am a new user to Teams and think it has great potential but am disappointed that such a simple request as changing the default (or landing) tab is a “future”.
It was my first question as well as several team members.
Were any focus groups convened before Teams launch?
Is the technology that inflexible that moving tabs is a future?
You’re Microsoft ! You invented User Experience! Maybe it was Xerox hmmmmm