In California, if you have a creditor, you are required under the Rosenthal FDCPA to update your contact information with the creditor. This means that if you move, you need to call the creditor and give them your address.
There are no damages for not doing so. However, if the creditor, or a collection agency, sues you and they attempt to serve you at your old address, service may be valid. Don’t take the chance and update your address with the creditors.