Select the File menu and click Preferences. Select the Bible Book Abbreviations page.
SwordSearcher has a standardized list of Bible book abbreviations, but you can customize these to suit your own needs. For example, you may wish to change the abbreviation for Genesis from Ge to Gen., which you can do here.
Simply double-click an abbreviation in the list to change the abbreviation. Abbreviations you specify must use at least two characters, may not contain spaces, and must be recognizable by SwordSearcher as the book name you are setting. You may add an optional period to the end of the abbreviation.
You can click Reset All to Defaults to go back to the standardized list.