Viewing, font and colour preferences can be set using the 'Options' button when viewing differences.
Use the Options dialog to choose whether to view line numbers, how to handle whitespace, case and tabs and what percentage of a line needs to be similar to be regarded as a match.
Use the Fonts dialog to choose which colours and fonts should be used for displaying differences. A selection of standard schemes is available using the drop down menu or you can create one of your own.
Use the Find dialog to set preferences when searching for specific text.