You can change extrusion speed in host->printer settings for slow and fast. But you should know what this is not related to model print speed. During normal print speed is move speed and extrusion speed is computed from that while pure extrusion the speed is that of the filament.
Firmware retract settings are only used if slicer uses G10/G11 for retraction (which is ultimaker style), in all other cases speeds from slicer are used.
