New User Intro emails not working

When new users (clients) are added to my Knack DB, I expect Knack to automatically send the intro email. However I am finding that it is not happening anymore. The only way I can make it send is to edit the record where there is a field that asks (send intro email?) which is defaulted at NO. How do I change this default? I can't find that field anywhere to edit.

I don't want to have to write a Zap to do this, and I want it done asap so I don't want to write a task to do the same thing.

What am I missing??