1. Open following link: https://store.nero.com/myaccount/
2. Sign in using your email address which you also used when you bought the order.

After login, you will see below screen. 

 You can view following details:

• your orders
• getting invoice
• managing your subscription
• different payment methods

Click on one of these details to make wished changements.

Below is an example of Product/subscription information of an order. In the bottom part, there is also information about how to get support.