You’ll receive a Notice of Undeliverable Mail from the court if one (or more) notices to creditors were returned by the post office because their mailing address was incorrect. Typically, it includes instructions to add the new/updated mailing address directly on the form notice and send it back to the court.
Since this will ensure that the creditor will get all notices going forward, you won’t have to file any amendments to update the address. You should, however, send a copy of the form the court tried to send to them (usually Form 309, if you filed your case recently) to the creditor’s correct address to make sure the creditor is properly notified.
These notices vary somewhat from district to district, so if you’re not sure how to fill out and return the form, contact the court where you filed your petition and speak to someone in the clerk’s office about what you need to do.