Set to false:
$wgDefaultUserOptions["usenewrc"]
Set to true:
$wgDefaultUserOptions["rcenchancedfilters-disable"]
$wgDefaultUserOptions["wlenhancedfilters-disable"]
Set to false:
$wgDefaultUserOptions["usenewrc"]
Set to true:
$wgDefaultUserOptions["rcenchancedfilters-disable"]
$wgDefaultUserOptions["wlenhancedfilters-disable"]
Are you sure you want to set rcenchancedfilters-disable and wlenhancedfilters-disable to false? I think it's true (or 1) what you're looking for.