By default when you open the Swaption Forward Rates page the system displays the market rates according to the selected cut-off time in the pricing page from which it was opened.
Subsequently, when you click the Refresh button this updates the Swaption Forward Rates page with the market rates for the selected cut-off time. For more information on the available cut-off times see Changing the Market Data Cut-off Time.
Clicking the Refresh button not only updates the relevant volatilities, but also automatically recalculates each corresponding volatility and straddle price as well.