Stereo losing radio stations every time I remove the ignition

Hi all, I've had this issue since I bought the car 4 years ago, been a problem for me as I use Spotify via bluetooth,  but I'll be selling soon so wanted to get it fixed.

When I bought the car, it had an old JVC head unit, and every time I took the key out the ignition the radio stations would be lost. Assumed it was the head unit so bought a new one, and have the same issue!

It's going to be a simple wire to the wrong connector I'm sure, but I want to do it right… can anyone point me in the right direction of a diagram or solution please?

All the memory is lost - time, radio stations etc - so it's going to be a case of there's no permanent feed to the stereo?

Thanks! 

The issue is that you have a switched Power for the Radio and a direct power for the Memory.

On after market radios it is a Yellow wire that you have to go direct to the battery.
The Red wire is for the switched power which I usually grab off the hot side of the Defroster switch Black/Yellow wire on the connector side.

see:
https://www.cabby-info.com/Files/AudioSystem.pdf

Agree with the above.

Briano1234, Great link, I have just printed it for future reference.