The constituent interests tab will let you opt Constituents into web interests, which conditionalize web content, but email interests are handled differently. Email interests determine which emails (newsletters, reminders, etc.) a constituent will be sent, so they are handled in the Email Preferences tab.
  1. Locate the constituent profile in Constituent360
  2. Go to the "Email Preferences" tab and click on the button that says "Edit Site-Wide Preferences"
  3. Next to each email interest, you will see a dropdown where you can select "Subscribed" or "Unsubscribed" to opt them in or out of the interest