It the model flies with it's fuselage parallel to the ground, your horizontal stabilizer has too much positive incidence and the up elevator is producing canceling out what that produces: a nose down pitching moment.

If your model has no ill handling tricks that show up with changes in airspeed, live with it. The tail is producing what is needed for trim. It could be doing it a bit more efficiently, but improving the efficiency would require a fair amount of hacking to get a better AOI.

If the model is flying around with the fuselage nose high, the AOI of the wing is the culprit. To fix that could require hacking up your wing hold down setup so the wing AOI held the fuselage parallel to the ground when the wing AOA was correct for the load it was carrying.

It's a trainer..... and you already know how to build....