Just renewed but when I try to insert new activation number......I can't get in

When I go to settings on Interface it asks for my password. I enter it and it says it’s wrong. How do I change it so that I can get into the “registration” to enter my activation number, etc. It gives no clue as to how to reset a password on the interface and it’s driving me nuts. Anyone help me please?

https://www.avast.com/faq.php?article=AVKB217

Thank you so much. It is now fixed.