Clicking on any of the email of a client in the list will take you to the overview page which has contact details and other important information regarding their job position and any custom payment terms (grace period) you have agreed with them.
Changes can be made to these details at any time but you must save them before exiting the window.
The manage users section displays a reset link for their password. In the event the customer is unable to log in and cannot reset their password on the log in screen. Copy this link and send it to them. They will be take to a reset page allowing them to create a new passoword for their account.
You can also block users from logging in using the block user button.