You can change your own font colour, size and the actual font as well.
Click the T at the bottom left of the chat room and choose the settings that you would like.
You can try these out in the 'Test and Help Chat Room' first if you like, click this link to go in to it now or find it in the column on the left here at the bottom.
Here is an image showing me in the chat room with before and after fonts. I have put a red spot on the image to show where the T is.