Only place where you can select color/extruder is in "Object placement" tab. Once a model is loaded it has on the right tab a name entry and right to name there is a select button to select a extruder. It will then color the model with that name with color stored in printer configuration in host.
But note that the print color depends on filament and mixing ratio assigned in printer. It is not set by host at all except if oyu have added the proper g-code at the start using the firmware commands to set them!
