How do I change family member details?

Go to My account and choose the Family members tab. You'll find a drop down choice of your current family members. Choose who you'd like to review and their details will appear in a form below. Make any necessary changes and hit Submit.

You can also choose to receive your family member's personal messages yourself instead of them, by ticking Send their personal messages to me instead in the same form. See Can I receive my family member's messages instead of them?