Ok so I too did have the problem where all the settings, such as date, time, radio channel, etc. were not working. So this is what I did:
First, the cable already has a fuse, so I unplugged the BATT cable (yellow) as marked with a red circle below. That connector removed is like a long spade connector (I don't know the right name for it).
Next I made a wire approximately 300mm long. One end is crimped with a male bullet connector and the other end, a female spade crimp.
I then connected the female spade crimp onto the connection that I just pulled out before and crimped them together. The male bullet was then connected onto a Fuse tap blade, just like this one:
Then I plugged the fuse tap into the spare slot as show in the diagram below.
I chose this way over wiring straight to the battery because the fuse box is much closer to than unit the battery is. Now everything such as setting saves when I turn the car off then on again, and the unit now automatically turns on and off with the car.