On the demographics page, your age and ZIP show up read-only — you can change the consent state, but not the values themselves.
That's because both come from signup. Your age is calculated from your birthdate, and your ZIP is the postal code on your profile. Changing either requires editing your profile, not the demographics page.
You can still change the consent state on those fields — set age to anonymous or disclosed independently from ZIP. They behave like every other field once consent is set.
Why this is split: birthdate and ZIP are identity-shaped data, not just demographic flavor. Editing them needs to go through profile so it's clear what you're doing. Demographics just borrows the values to show you what brands would see.