Unit keeps losing all my pre-set stations, every time I shut it off

Inside the unit will be either a battery or a memory retention capacitor. This keeps power to the chip that stores the setting. If the battery or Capacitor is faulty, then the chip will not have the power to save any settings.
The Capacitor will look something like the image below.

I don't think you have the memory keep alive wire attached to a constant 12V+ source. This is why it is not keeping set stations and reverting back to demo more every time it is switched on. Usually the memory keep alive wire is yellow.

Hi, the problem is likely in the wiring or possibly a burned fuse. There is a separate wire to the radio that is always hot and keeps the station and clock settings while the key is off. If you tell me the car model and year, I may be able to tell you which wire and fuse to check. Was this working originally or has it never worked?

It sounds like you need to make sure the yellow wire is going to a constant power source. That is a source that is still hot with the key off.

Station Pre Set:
You can save 4 pre sets on this radio (1-4) tune the radio to the station you want to save then PUSH and HOLD one of the pre set butons until the sound returns, the station is saved to that pre set. Repeat for the 3 presets.

Clock:
Hour: Push and hold the CLK button and at the same time push the SEEK button to adjust. < decrease hours > increase hours.
Minute: Push and hold the CLK button and at the same time push the TUNE button the adjust. < decrease minutes > increase minutes.

your deck has two power sources a main for when your car is turned on so the radio kicks on and a remote which is always on keeping stations and clock powered passively so whoever installed it did it improperly or do to road wear and tear it was jossled lose and can simply tightened after pulling the deck out

There's no clear all settings there. You need to manually delete each saved station. Try to unplug the power of the unit for few hours and check if that clears all.

your constant power wire is not hooked up or it has come loose that is why nothing will stay saved on the unit have it looked at and see if they wont fix your problem cheap...... its a easy fix

Most probably the memory capacitor / battery inside soldered to pcb

Have same unit, exactly the same problem: station presets lose setting when power is off. I've opened the unit; there is no apparent battery of any kind.

As long as the unit is powered up, the station pre-sets seem to hold. There IS a capacitor across the power switch. Some A/C will therefore be transmitted into the unit when plugged in, even with the switch off. If the capacitor is open, no charge will enter the unit when the power switch is open. I will probably replace this capacitor and see if that fixes things, but it may take several days to do so. Has anyone else tried this?