Your problem, if I am reading the specs on your plane corectly, is with a high lift high wing your aircraft will nose up when you increase throttle and pich down when you decrease. The web site also says 3D capable which only aggrevates the problem. Trim is the most likely cause of the pitch and turning problem. A good technique for trimming a small light aircraft is to go a field with tall grass and hand launch with the motor off and adjust the trim for a straight moderate descent. It may take many throws but it will be worth it. Remember also that when you change the throttle in flight it will change pitch as well.