That overlay "The same goods are used by other NPCs..." is not really handy - I know it's tempting to click "Edit just for this NPC" just to see what it does, but this action is irreversible and potentially harmful. Along with what Escanor suggested about copying or cloning settings from different NPCs, I would like to propose a following concept:
In each window (NPC, NPC goods, NPC recipes), add two radio buttons (one must be selected, the other one not). One would say "edit directly", the other one - "use a template". Editing directly would be the same as "Edit just for this NPC" in the current version. If the template is selected, then you can use a handy window (something similar to the item finder) to choose a configuration that's already present - e.g. from any other NPC. The window looks the same then, but there's a bold text saying "you're editing a template used in N other places", and there's also a button to clone that template -> so the you could base on it, but still make changes specific to that particular, single NPC.
I'm writing this down mostly for myself 
Have a good evening!
I'll publish a video tomorrow