The first setting is your choice of RGB working space. This dictates the format in which all the colour information in an image is stored while you are working on it. A common mistake is to set this to your monitor's colour space, but that means the colour range of your monitor will limit the colour content of all your work pointless when it is destined to be displayed and printed on other devices. Instead, the correct choice is a theoretical colour space that can represent the widest range of colour accurately, usually ‘Adobe RGB(1998)’. The CMYK working space, however, should represent the actual printing press you plan to use, as you won’t normally be editing images in CMYK mode