@SteveITS yeah I would highly doubt there has been much work on the forwarder (dnsmasq) in quite some time to be honest. I am surprised that anyone would still be using it to be honest.. I mean it can do some things unbound can't like forward to multiple NS as the same time, etc.
But if you can't figure out that the custom options box is what they were talking about - not sure what to tell you ;)
Now if there was 2 boxes, one labeled advanced, and the other custom - and putting it in advanced didn't work because they called out the wrong box - yeah that could be problematic.. But there is only one possible place such commands could be put into that gui form.