Help with Dual WAN Setup of Sophos UTM 9

I am not sure who out here may know the Sophos UTM products but I have a fairly simple question I believe.  Our UTM is configured with two internal networks (1 for our office network and 1 for our Guest WiFi).  We are also running two ISP's so we have two external WAN interfaces.  Currently both internal networks are going out the primary external.  I want to configure the firewall to have each internal network go out through different external networks.  

If possible I then want each external interface to be a failover for the other.

Not sure how much of this is possible but that is what I am trying to get configured.