Hello @Dave6051 !
IGMP querier should be enabled per L3 interface, e.g. routed port or Vlan-interface. In general all you need to do is to:
1. Enable multicast routing (global command 'multicast routing')
2. Enable IGMP on respective L3 interface (interface context command 'igmp enable'). By default IGMPv2 is enabled
Example for Gig0/0 interface:
system-view
multicast routing
interface Gig0/0
ip address 10.0.0.1 24
igmp enable
After that if your router is the only IGMP device on this L3 network, it will become a querier. If there is another multicast router with IGMP enabled, then there is an querier election mechanism and the querier will be the router with lowest IP address.