The trim in all aircraft seems to wander to the nose-down extreme setting while setting aircraft up for the flight.
It can be adjusted to the proper take-off and seems to hold position when AP is engagued; but if the aircraft idles on the ground for any length of time, the trim creeps back to full nose-down.
…
Most probably a forgotten binding on any Controller. Check all Controller Settings, guess you will find something
@OriDarkwind
Confirm the AP is OFF when this happens?
If not, it’s correct that the AP trim will ‘creep’ either full up or down.
Exactly – you cannot have the AP “ON” when the plane is not flying, as it cannot control the plane, and will typically run its controls to limit.
The only exception, is if you want to TEST some of the AP functions when on the ground. ie AP Heading operation, where, (if you have a FF Yoke/Joystick", you should see movement on the control, as you submit a AP heading deviation command etc etc)
Also, MAKE SURE that the AI Pilot is OFF, unless you really intend for him to take over flying the plane, AND over-riding the AP.
I suspect that MANY of the AP not working / crashing the Plane reports, are from “Pilots” who have left the “AI Pilot” turned ON !!!
You misunderstand. The Trim goes to the ‘down’ limit with that AP off. It happens while the plane is sitting at the stand.
AP is off when this happens.
Then it’s, as @Sunday748 wrote, most likely a binding/assignment problem, e.g. a double binding.
AI copilot disabled?
It shouldn’t.
As PZL104 mentioned, if you have no assists on, it sounds like a key issue.
If there is no duplicate commands, is your key for the trim unknowingly sending a signal to the sim?
Did you try assigning a different key?
Okay, so it appears that when I plugged in My Xbox Controller, MSFS2020 decided to add a number of new assignments that were not there previously.
After removing the controller’s assignments for trim, flaps, and a number of other things, the issue has gone away.
Thanks for all your help. I would close this topic as resolved.
In your initial post, use the 3 dots to mark the thread as solved.
This always happens to me, I do not have any duplicate command, I have calibrated the joystick 1000 times and the same thing always happens,whatever I do it always goes down, I have looked at everything, and everything is fine but I do not know how to solve the problem this so tedious
Is the trim bound to a key on your controller?
If so, change the command to a different key.
The key could be slightly sticking, causing the command to repeat.
that’s not even how trim in an A320 works… this default aircraft is far from even allowed to be used in a flight “simulator”… 
It ID very annoying. In the PC haven’t been able to figure out
for those of us only using the Flight Yoke, where can we look for this additional assignments that can be affecting it? it is happening to me just as you describe it
These are found under Control Options in the sim.
Thanks for taking the time. Already looked in the options and all seems ok 
. Any other ideas?
