Hi Alain,
To create a DCA group, you need to press the mix button at the bottom of the DCA channel strip you wish to use, then press the on/off buttons at the top of the channel strips you’d like to be part of this group. For Mute Groups the procedure is the same, but you need to turn a DCA into a mute group by right clicking on the DCA channel and selecting the mute group menu item.
To save your configuration you will need to archive a show from the show manager, and then restore it when you open editor in the future.
Hope that helps?
Colin A&H