Hello and thank you for your post. I am a master certified GM tech, with 15 years Saturn experience,and can help you to resolve your issue.
the rcl button top tight on most radios sometimes on the left...you hold that button and press the seek left and right buttons or the tune left and right or track left and trght buttons.
The radio has the instructions clock set, hr, min embossed lightly on the face plate just under the buttons I am talking about.
Do this with the radio off.
That should do it if you have a factory radio