4D printing is the method of creating 3D printed objects that change their forms in a desired manner on being exposed to a stimulus. The degree and kind of form change is dictated by the printing parameters. Typically, an FDM 4D printed object consists of two parts – the active layer, which responds to the stimulus by expanding or contracting, and the passive layer, which remains unaffected by the stimulus. The difference between the expansion rates of the two results in bending. Since the active layer brings about the form change, previous researchers have  focused on the effects of active layer printing parameters (like material, printing speed, printing path, printing temperature, and layer thickness) on the change in form. The passive layer has been virtually ignored. Through this paper, we show that the passive layer printing parameters play an important role in dictating the form change output of 4D printing. We study the effect of passive layer material (PLA vs. TPU), printing path (at angles of 0°, 45°, and 90° to the printing path of active layer) and its position in the print (top vs. bottom) on the actuated forms. We conclude that each of these parameters affects the bending angles and final geometries of 4D printed items. Finally, we discuss the importance of studying passive layers and how it might help expand the design space for 4D printing.