The layout is not customizable over a bridge. They can only be changed when on a point-to-point call, which is controlled by the endpoint layout options. More layout options also became available in the TC6.0 firmware release. Here is a link to the quick start guide, which goes over the different layouts and other settings.
This table lists the ports used for various activities on the Cisco
WebEx Telepresence network. Please make sure to configure your network
and firewall so that they do not prevent connectivity on the ports
listed in this table.
If the Cisco WebEx Telepresence service does not work as expected after
activation, you can perform a factory reset on your device, as described
in the appropriate section:Performing a factory reset deletes any
contacts you entered.Perform a factory reset...