The "default" appearance will be whatever options you select on the Appearance Tab in the inspector for this layout object to specify fill or text color. It's what shows when no conditional format expression evaluates as True.
Thanks. Using that simple answer helped me simplify the formulas that were making the messages "Set Payment Status" and "Paid" so I simplified the way for a Status field to know it was paid or not paid and it performed the way you said. Thanks.