How does one change their credit card information?

How does a person change their credit card information? I have looked in all of the places and cannot find a place that a subscriber can change their billing information …at all. If I do not receive some sort of comment back, I will have to cancel this entire account.

Tried it in your order information ?
https://store.avast.com/DRHM/store?Action=DisplayCustomerServiceOrderSearchPage&SiteID=avast

https://www.avast.com/faq.php?article=AVKB24#idt_01

I am not able to access the portion of the account to change my credit card information. Please advise of the steps to change my credit card. Thanks

Why aren’t you able to access the portion of the account to change my credit card information ?
e.g. what errors are you getting or what information do they want that you can’t provide, etc.