This dialog is available from the Options / Report Preferences... menu command under any Report window. The benchmark preferences are only available in the Professional and Advisor versions of Fund Manager.
This dialog allows you to choose an investment to use as a benchmark when calculating statistics such as Alpha, Beta, Correlation, R-Squared, and Standard Deviation of Returns. You can also specify a comparison period to use when calculating these statistics and the Standard Deviation of Returns. 5 years is the most common value, but you can select any year time span desired. You can also specify a return to use as the risk-free return in the Alpha and Sharpe Ratio calculations.
Create Investment from Portfolio Dialog