How do I change item title back to Customer name? Now it shows Doc number

So I have customized Warranty doctype and for some reason it shows Numbering as item title and not customer name as title like before. See example:


What settings do you have under Customize → Naming section for Naming Rule and Auto Name?

Hey, thanks. I figured it out. I had customer field in doctype, but naming seriies in customise form. So it was overwriting.