Another thing on trim. Airspeed is everything with trim, it controls how much laminer flow is going over the control surfaces and the trim tabs.
So if you give nose up trim and you are going 150kias its going to take alot more trim tab to stay level then with will with say 30kias due to how much air is flowing over the control surfaces and trim tab. So when you speed up the nose is going to want to keep climbing. As the air gets thinner as you climb it will take more aswell.
So maybe it takes 2 degrees of trim at 350kts to stay level it may take 10 degrees at 150kts.
Trim is somthing you have to play with alot. It just takes pressure of the control stick or yoke by not making you correct for conditions. The plane will fight you in real life up or down with pressure until it is trimmed right!
Hope this helps!