Colour Settings is where you are able to change the look of the Blocktrix program. After clicking on the Misc. Settings button at the bottom of the program, simply left click on the words Colour Settings located at the left side of the program, as seen here:
After having done that, you should see a screen that looks like this:
The items are all self-explanatory. To change a colour for the respective item, simply left click on the coloured button to the right of the item you wish to change, which will bring up a colour dialog allowing you to choose the colour you want. In the case of Chat and GameLog Colours (where GameLog is the area in the fields where attacks/defenses are shown), you are able to change the colours of the text displayed there by clicking the coloured buttons below the caption.
To go back to the default colour settings at any time, simply click on the button in the bottom right, marked Reset.