Yes, NFL My Playbook does support Team QB leagues.
To access this setting, go to the My Leagues page. Then, click the vertical ellipsis next to the league you would like to edit and select League Settings.
When you enter your league settings page, click the "TQB" drop-down menu and select the amount of starting Team QB positions your league uses.
Please note that if you have Team QB as a position in your league, but do not have QB as a position, please set the QB position to 0 using the QB drop-down menu.
Once you have finished editing your settings, click the blue "Save Settings" button at the bottom of the page to save your changes.