Hi,
All of the previous is good advice. Try trimming the plane out at a higher throttle setting and make that your cruise speed. It will still climb if you increase the throttle above that level.
Also in keeping with the LEARN TO USE THE THROTLLE theme try setting the level flight throttle setting much LOWER and learn to do things like low and slow figure eights without ever leaving the area directly above the runway. One wheel touch and goes are fun two.
Practice axial rolls, the rudder will be required to get it right. Also try inverted and see if you can fly the complete circuit.
Good luck!