How can you get a dual-xd1222 audio recevier retain its memory once the car is turn off?

there are 2 power wires that go into the back of the unit. the yellow wire must always be directly connected to the battery. the red wire is switched; when this wire gets power it turns on. the yellow wire must get constant power so it can save your stations. think, you know how when you change the battery in your car or it goes dead you lose your stations and clock? this is because the yellow wire lost the constant power it needs to keep your stations