I agree with the rest that 1/4 turn is a big adjustment. Now to the trim issue. Do yourself a huge favor and make NO adjustments until you measure everything and check your CG. For an aerobatic bipe I really like the settings that Goldberg used on their Ultimate. Those settings are engine at zero, both wings at zero and stab at + 2 degrees. I would be interested in knowing what H9 has the CE set up at. Another thing to consider is CG. If you are nose heavy and it required up trim even at 1/2 throttle then at the higher airspeed that trim becomes more effective and she climbs. Did it seem to want to land fast? If yes, that is another sign of being nose heavy.