Basic option are:
Use Syntax Formatting
Enable this to have Source Insight display source code with syntax formatting. If disabled, then source code will display with no coloring or font changes.
Use only color formatting
All non-color formatting properties, such as font size changes, or bold and italics, will be suppressed. Display tokens will only contain color changes. This is similar to how earlier versions of Source Insight displayed text.
Use no color formatting (monochrome)
If enabled, then Source Insight will suppress all color changes. Text will be displayed in black and white and gray.