Other than taking bookings, all action on a specific member starts by accessing the information for the member via the admin home page.

Type part of the members name or email address into the search box on the Members section of the admin home page. As you type a dropdown list will appear with matching name. Select the required member from the list.
select member

The members status page is the gateway to managing all information about a members and their bookings
member status page
While on a members page you can swap to a different member by typing a new name here
search for member
And if the current member is in a family group you can use the family data shown to flip between family members
family switch