Hi @ooa ,
What OS is installed in the computer?
Have you checked the other printing preferences in the printer properties?
Here is a link that may be of some help.
Select your OS and then select either Advanced printing methods (Windows) or Set print Options Macintosh (dependent on your OS), and then select any link that mentions quality or colour to see if the adjustments resolve the problem.
If adjusting the settings does not resolve the problem, check that you have the Brother printer drivers appropriate to your OS installed and that you are not using the "generic" OS drivers for your model printer.