You don’t need to factory reset anything unless you decide to sell or give away the Arc.
Simply remove the Sub and Era 300s as surrounds from the Arc in the Sonos app. Then set up the Arc Ultra in the app and add the Sub and Era 300s as surrounds to using the app. You can rename the Arc and Arc Ultra in the app too.
If you plan on getting rid of the Arc, perform a factory reset AFTER you complete the steps above.
The Arc and Arc Ultra both use the same power cable.
