The "Change password" button is not updated to password type field when form fields are updated. For example, when changing Authentication value.

Steps to reproduce:

1. Go to Administration->Media types (6.0, 6.2.) | Alerts->Media types (6.4, master)
2. Create media type
3. Add data:
   1. Name:  test
   2. Type: email
   3. Authentication: Username and password
   4. Username: username
   5. Password: password
4. Create media type.
5. Open the ''test'' media type
6. Change authentication to "None"
7. Change authentication back to "Username and password"

Result:

The Username field is updated (cleared).
The "Change Password" button remains visible.

Expected:
Password field is reset to password type field when form fields are updated.