The WinKeyer Serial Port popup list displays all active serial devices on your computer. When you choose an entry on the list, SkookumMorse abandons its current WinKeyer connection, if any, and tries to connect to the newly-selected entry. If the attempt faults, an obscure error message is posted and the None entry is selected. You might want to choose the None entry to release your WinKeyer after saving new standalone mode settings, so that you can test them without quitting SkookumMorse.
The My Call value sets the string that is sent when SkookumMorse encounters the grave accent (`) character in a message or in the Keyboard text field. The value can be anything that WinKeyer USB recognizes.