Need to add PS3 Engine evey time I power up

Dan, try this:  power up the track on which the loco is sitting and hit startup.   You should hear sounds. Wait at least a minute.  Cut power to the track (do not hit shut down).  You should hear the sounds continue for about 5 or more seconds.  Do you?

If not, the loco is not saving the data to its memory.  SUpercap may be bad or disconnected.

That's not good,

IDs should stick with the engine unless edited. factory reset or  the ID is taken by another engine when adding  .

I would delete  the old address and the recently added one and add again  to  see which address comes up.  Sometimes not quite right.

Here what I would do, start by doing a reset via transformer I think it is 1whistle and 5 bells or vice versa. Put power fro 1to minutes to get the capacitor charged to a good point then shut the power down, add it , factory reset via DCS then add it again. Try to change the ID, delete after letting the power and engine sit for several minutes, then delete it then re add it. Maybe Marty Fitzhenry or Barry Broskowitz could give you similar steps to what I would do. Hope this helps.