What must the carrier change when filling out PS Form 3546X?

When filling out PS Form 3546X, the carrier must change the original mailing address. This form is specifically used for notifying changes in address for mail forwarding purposes. Updating the original mailing address is essential to ensure that the mail is correctly redirected to the new location, thereby maintaining the efficiency of mail delivery.

The other options focus on aspects that may not directly pertain to the primary function of PS Form 3546X. For instance, while the customer's name and initial order details may be relevant in other contexts, they do not directly relate to the necessity of updating the address in this specific form. Additionally, the duration of mail forwarding is typically defined separately and does not require alteration of the original address, making it less relevant in this scenario.