Your New Customer Offer should be set up by your Account Manager during your onboarding appointment; however, you can always make changes to it in your Merchant Center. To begin, click on the Campaigns menu, and choose "New Customer."
The first block of text under the infographics will have your default New Customer Offer. Click "Edit Offer" to the right. Review the expiration timeline, title, offer, tagline, and fine print. Once your edits are complete, scroll down and click "Save."