I’m not sure I’m the best person to answer this since I have plenty of problems with trim of my own (but mostly just once in the air). But I can’t resist. Lol
If you right click on the screen during play, you should see a popup menu that allows you to select view point. There are two cockpit views and one of them has an extra set of buttons that allows you to pull up certain controls such as the radios, the throttle, and the trim. The other cockpit view allows you to “turn your head” and look around, where you can turn to look at the trim controls.
With either of these settings you can use the mouse to alter the trim as long as the mouse isn’t set to yoke control.
My joy stick actually has two buttons that are mapped to pitch trim by default.
I imagine that there are some keyboard keys for trim as well but I’m not sure what they would be.
I’ve been playing FS-X for about a week now and have not noticed any problem with trim starting out. I would be more inclined to think that the problem described is that the joy stick is not properly calibrated. Double check that before trying to adjust trim.
On the trim control display you can see when things are “centered”. I don’t know, but I would think starting out with everything centered is probably the best way to go.
Also, if you manage to get it line out once, you can save the game by hitting the semi-colon key. I’ve been inclined to taxi my plane to my favorite hanger (near home), kill the engine, and save the game, so that I can have a default game start that has the plane sitting on my home taxi way with the engines off.
Oh, and one last thing. I was confused on the first training mission; I found out the hard way that that glider has no rudder, so rudder controls will do nothing except steer on the ground.
Good luck and good flying!