If you change the Label of an option (answer) for an existing question, any prior and future responses using that option will continue to be displayed in Poll results, associated with the same answer. The new Label will display in the Poll Results.
If you change the Value of an option (answer) within an existing question, any past responses will display using the old or prior Value and Label. Any future responses will display separately as a distinct answer using the new Value and Label, even if the Label has not been edited.