24 hour clock / 12 hour clock?

[sabotage 0]

I've searched the forum but didn't see the answer.

 

I'd like to switch to 12 hour clock, 1:00 a.m. to 12:59 p.m. - rather than 0:00 to 23:59

 

Help?

[ruairi 0]

Can't be changed from 24hr clock.