To change the URL for your Design Proofs, first, go into the Shoot and the Design Proofs. Select the three dots on the right-hand side of the Design Proof you wish to update and click "Settings".

Once inside the settings, click the Link box in the middle of the "Settings" section and enter the desired URL. Click "Update" at the bottom to save your changes. You can now share the new link or e-mail it through the settings option.