Need Help With Wiring In Eg

[imported_O3DigitalBath]

When i first got my car I realized that the radio (stock one) wouldn't hold a preset, when the car was shut off all the radio presets would go away, I was told that it was because my 12v constant wire to the battery was switched with some other wire....(i could care less about that).....

Anyway i was at the junk yard today and picked up a clock for my car i put it in set the time and i was all happy to get something new, a while later when i got back in my car to go somewhere I noticed the clock time was reset

to make it short my radio won't hold the presets and clock doesn't hold the time when the cars off.....I'm thinking that i am missing some sort of constant 12v source or something but i don't know much about the factory wire set up......any one have any ideas? I'd like to fix this problem