If the NAME of a customer is changed, it updates in an already existing Sales Invoice. If the ADDRESS of a customer is changed, it DOES NOT update in an already existing Sales Invoice. Is this a bug?
Bug or feature?
It is probably a good idea to think about what your would actually prefer.
A name change for an existing customer may well be due to a data entry error so fixing it everywhere would be good on that occasion.
A customer may change address or even operate out of more than one address in which case keeping existing address would be desirable.
Is your use case typically different?
There is also a good chance that, if the name of the customer changes, they have changed legal identity. In that case, they are a new customer.