Here you can select the key to be used when OpenPGP-signing messages written with this identity in effect. For brevity, only the short key id of selected keys is shown. Hovering with the mouse over the key list will show more information in a tooltip.
To clear the label press the Clear button.
To change the selected key, press the Change... button. A dialog listing all secret OpenPGP keys will be shown allowing you to select the one to use.
