I can't change my alarm time settings

I own a 5th generation iPod nano and I regularly use the alarm clock and it works fine until now.

When I set a new alarm and choose the exact time I want it to ring, I go back to the alarm main menu only to find out that the time I selected has changed. Every time I go back to the time settings and correct the time I want, the final saved time is different.

I already tried to reset my ipod twice, I even restored it but the issue remains.

What should I do ?