If you ever need to adjust basic info, change a password or edit values under any account in your system you can easily do so through the USERS section of your admin backend.
You can search for users 2 different ways:

1. By e-mail

2. By Last, First name (Keep in mind that Last name will filter first and after you input a (,)*comma* you can input the first name of the customer)

Depending on which type of account you open/expand you will see a different setup for each of them, reference the pictures below to get a general idea of how these account types look.