Some servers have multiple network interface devices. cPanel offers the ability to set the default device to be used when interacting with IP functions in the WHM interface.
First, log in to WHM as the root user.
Next, navigate to the "Basic WebHost Manager Setup" page.
The setting to adjust is titled "The ethernet device onto which new IP addresses are added. Devices detected with at least one IP are listed in the drop-down, or you may specify another device."
More information on this setting, and others on this page, are detailed here.