You can use the setting dial to set the frequency during operation even if Pr.77 is not set to "2".
Setting Pr.77 to "2" allows for changing the parameter settings during operation.
With the initial setting, you need to turn the setting dial to select frequency and press the "SET" key to accept it.
Setting Pr.161 (Frequency setting/key lock operation selection) to "1" allows for using the setting dial as a potentiometer.