To prevent automatic failover, you can use PowerShell to configure Get-ClusterNode -Name "NodeName").NodeWeight=0. This command removes the vote on each node in the disaster recovery site. Then you can use Start-ClusterNode -PreventQuorum on nodes in the primary site and Start-ClusterNode -ForceQuorum on nodes in the disaster site to force failover. There's no graphical option for preventing automatic failover, and preventing automatic failover isn't recommended.