I should have asked at what throttle setting does your trainer climb at? Trainers are built to climb at full throttle, cruise along at level flight at 1/2 throttle and descend at less than 1/2 throttle. Its a safety thing, if something goes wrong, go full throttle and the plane will climb. If the plane is still climbing out at 1/2 throttle or less then I would mechanically adjust as mentioned above for level flight at the 1/2 throttle setting. If you adjust for correct trim at centre then you don't need to remember where the trim was when you flew last. If you do this for all your other planes that you get, then model memory isn't an issue. About the flaps, when you lower them they create tremendous lift which is why the plane will nose up if you aren't ready for it and adjust the trim accordingly. Its the same for full size planes as well.