When you specify this option, PGPMenu will ask you which UserID you'd like to use, and will then start to use the key associated with that UserID. The default choice for this option is to stay with your current UserID.
This option will not change the UserID on your key; it only allows you to select which key you will use, based upon the UserID.
When this finishes, PGPMenu will wait for you to tell it to return to the configuration menu.