Go to the .cfg file, and look for the font which has the matrix (would be near the top of the CFG file, then change it, I've pasted an example from the New Routemaster Below. You will need to change the font name and the RGB Colours. You may also need to change the size of the font if it appears too big or too small after you have changed it. Remember, the higher the number, the smaller the font
[texttexture]
Matrix_Terminus1 (It will most likely be Matrix_Terminus in the solaris)
P22 London
300 - Size of the font horizontally
70 - Size of the font Vertically
0
255
255
255