nicht root menu, sondern nur submenu aendern.

gistfile1.py

def rename_team(team_number):
    """rename teamnames in the teamnamces dict and in the menu dict"""
    # hier kommt nicht der neue name
    new_name = input("please enter new name for team number {}: ".format(
        team_number))
    if new_name == "":
        print("nothing renamed")
        return
    team_names[team_number] = new_name
    # outcommented code does not works, renames root entry :-(
    # access the value of key "root" , entry [team_number], first entry
    #menu["root"][team_number][0] = "Manage team {}".format(new_name)
    # submenus

    # hier wird das submenu geaendert
    key = "team{0}".format(team_number)
    menu[key][0][0] = "show info of team {}".format(new_name)