How can I change the benchmark within my portfolio? 

Users can set any fund, sector, index, currency or portfolio as a portfolio benchmark. Within any portfolio, simply click on the small arrow next to the 'Add' button and the option to 'Add as benchmark' will become available. This will change the benchmark only for this one portfolio.

To change the default benchmark for all portfolios, you can set this in the 'My Settings' found in the settings section.