When creating a new subscriber or editing an existing one, you will need to add login details. You can find the login panel as shown in the screenshot below.

This will open up a popup which will contain the logins for that account. These logins can be edited, activated, disabled or deleted. 

For the example below, we are going to create a login for murray pioneer, by selecting the login group as murray pionner, adding a username and adding in the password.

It will add the login once you hit update to active it.

You can also edit the login by clicking the edit button, but please keep in mind that as a security feature with CRM the password is never exposed when editing a login. This means that if a customer asks for the login details for their account, it's best to just reset the password and provide them new details.