There’s no way to change between the two, per se. For MDA, one would use the orange bug on the primary altimeter. If the MDA is, for example, 1300 you would set the bug over the ‘3’ on the altimeter. If you are conducting a CAT II or III approach and need DH, that is located on the EFIS Control Panel by the Captain’s right knee. At the top of the panel you will see a knob and a digital display that allows you to select DH. The DH value will also display on the PFD.