Forecast - How do you reset the forecast line?

Hello,

I'm having an issue where I created a Forecast line on a Line Chart near the end of March. Now that we're in April, I no longer want to show March as a "forecast" since now the month has ended. How do force the forecast line to no longer "forecast" March, and forecast April?

In other words, in the below picture, I don't want to see upper and lower bounds on March because March is now final:

Thanks,

Nick