While logged into V3, click on People view (person icon, gold circle in image below). Then select the category the person belongs to. In our example, we chose Mobile which is a subcategory under Phone Type (brown box in image below).
Select the person whose email you wish to change. In our example, we chose Audry Jaffrey (gold box in image below).
Information about the person would be displayed to the right. The email would be displayed in two places: at the top of the profile and also under the details (two gold boxes in image below).
Hover over the email in Individual Details to bring the option to Edit (see image below). Click on it.
Input the new email address, and then click Save (see image below).