Enabling Preview Features in Power BI Desktop
As the Power BI Desktop team releases monthly updates, some new features are released as "Preview Features". You can easily enable these features through the option menu (File -> Options & Settings -> Options -> Preview Features). Once you select the feature(s), you must restart Power BI Desktop for the changes to take effect.
Click on File -> Options & Settings -> Options
Select Preview Features in the Option menu. Select the Preview Features to enable and click OK.
An additional dialog box may appear stating that Power BI Desktop must be restarted. Restart Power BI Desktop and your feature(s) will be enabled.
After that, you are ready to try out the Preview Features.
Sam Lester (MSFT)