Hello Petro,

In order to allow existing WordPress users to log both into WordPress (or WooCommerce, or some membership plugin) and Amelia using the same credentials, customers and employees in Amelia need to have "Amelia Customer" or "Amelia Employee" user role assigned to them. 

If there's a created WordPress user, but they don't yet have anything purchased through Amelia, you need to enable "Automatically create Amelia Customer user" in Amelia Settings/Roles/Customer, and then - after they log into their WordPress user, once they land on Amelia's booking page, their details will already be populated, and once they purchase the appointment, they'll be added to Amelia/Customers; linked to the WordPress user, and they will be able to visit the Amelia Customer Panel without logging in (since they're already logged in as a WordPress user).

If you already created a user with "Amelia Customer" but they haven't purchased anything with Amelia yet, that user won't be linked to any customers you have in Amelia, so before they are able to log into Amelia's Customer Panel, they either need to book an appointment while they're logged into WordPress, WooCommerce, or a membership plugin, or you need to create a customer by going into Amelia/Customers/Add Customer. When you create a customer, link that customer to the WordPress user, and that's it. After that, they will be able to log in with the same password that's used for logging into WordPress.

Please take a look at our video about this: https://youtu.be/nm7f7RDSYow

Please note: If you change the password of the employee, or the customer through WordPress, the same password will apply to Amelia's Panels, but if you change the password through the Customer or the Employee Panel in Amelia, that password will not be applied to the WordPress user role. This is because Amelia doesn't require a WordPress user to be created in order to grant access to the panels - that is optional, and Amelia can't modify the password for WordPress users.