ORIGINAL: riadh
Yes I can set the throttle to one setting and trim elevator to fly level in one wind direction but then the plane would respond negatively on the other wind direction travel.
I can trim the elevator for one throttle setting but the trim will change once the speed is reduced and that would cause serious down pitch
Yes, when you change throttle settings, the plane will want to climb or fall, depending upon which way you moved the throttle. That's normal. You can't trim the plane for level flight, add throttle and expect it to remain in level flight.
As far as wind direction is concerned, if the plane is trimmed for level flight into the wind, it should remain in level flight with the wind, assuming you don't change throttle settings. The AIRSPEED of the plane remains the same at a given throttle setting regardless of the planes direction with respect to the wind.
Groundspeed will change, obviously.