You keep all awards earned in your Naval service throughout your service. I'm pretty certain, however, that if you are commissioned and go back to the same community, silver pins earned turn gold once you are authorized to wear gold pins. IOW, if a sailor gets silver dolphins, then goes back to the sub as an officer and qualifies for gold dolphins, he only wears gold dolphins. If a sailor with ESWQ goes SWO, then he only wears the SWO pin. If a sailor with ESWQ goes subs, then he would wear gold dolphins and silver ESWQ. If an enlisted sub sailor goes SWO, then he would wear the gold SWO pin and silver dolphins. If an AW qualified sailor goes pilot or NFO, he only wears the gold wings. I'm pretty sure that is how it works.