The Field Name “HasOptedOutOfEmail” has not changed, just the Field Label. Any ideas as to why this is not updating or how to fix this? Thanks!
This is a standard field (you can tell by the suffix, anything ending with
__c is a custom field). You can't change the API Name of a Standard field. You can change the label, but not the API Name.
You could create your own custom field, and use that instead, which would let you name it whatever you want, but that comes with its own problems (getting the data back to the opt out standard field, having two fields doing the same thing, managing layouts, reports, etc).
I'd ask yourself why you need the API Name to be different. No end-user sees the API Name, just code, and developers.