When you join a new team, it's automatically shown in your teams list. You can choose which teams show up in this list and which teams will be hidden. 

See this Microsoft support article for further instructions: https://support.microsoft.com/en-us/office/show-or-hide-teams-and-channels-9d999159-4fc3-4f6a-acf0-02d786484734?ui=en-us&rs=en-us&ad=us

Related articles

Related articles appear here based on the labels you select. Click to edit the macro and add or change labels.