The Options dialog can be brought up by clicking the Options button in the toolbar, or by selecting Options in the File menu.
Check it if you want Tone Generator to play the last tone loaded from the previous run.
The device through which Tone Generator plays out tones can be selected from the Device drop-down menu.
The sample rate of the tone which you can choose from the drop-down list.
From the Tone Interval section you can specify the step the frequency of the tone should increase or decrease when you chose to increase/decrease from either the menu or the small toolbar, or when you press +/- on your keyboard. The step can be specified in Hz or in integer multiples of semitones (up to 12 semitones per step).