iOS 15
Fill out your Health Details in Health on iPod touch
When your first open the Health app 
, you’re asked to provide basic health information about yourself. This information helps personalize the Health app for you. If you don’t supply all of the requested information, you can add it later on the Health Details screen.
Tap your profile picture or initials at the top right.
If you don’t see your profile picture or initials, tap Summary or Browse at the bottom of the screen, then scroll to the top of the screen.
Tap Health Details, then tap Edit.
To make a change, tap a field.
When you’re finished, tap Done.