Tap your name in the top corner and choose My Profile. Your photo is under Change Photo, and your name is in the name fields on the same page, starting with First Name. Tap Save Changes when you are done.
The photo is the one worth doing
It is how people recognise you in the Circle, on messages and in the roster. A face reads faster than a name, particularly for someone who has three grandchildren with similar ones.
Any clear photo of your face will do. It does not need to be recent or flattering, only recognisable.
Changing your name
Type over it and save. Everyone in your Circle sees the new name from then on, and nothing else changes.
Use whatever you are actually called. If your family says Nan rather than Margaret, put Nan.
Your sign-in email
Your Email Address is shown on My Profile, but it cannot be changed there. If you need your account moved to a new address, open the chat bubble and you can ask Avery to connect you with a member of the team.
Do that rather than creating a second account. A second account starts an empty Circle, which is a much bigger problem to undo.
What you cannot change here
Somebody else's name or photo. Each person holds their own account and edits their own details, including your older adult. You are never managing a profile on their behalf.
The Account tab in Settings is a different place. It is where you would close your account, not where your name or photo live.