You seem to be on the right track with the plt, and the pzt dials. But just for a little more input on them I will share what I know. As you already know you cant change them without switching the #8 switch on the back to unlock. (to the left) The plt (pitch limit trim) Will adjust the range of the servos, If you turn to the left the range of the servos decrease, and to the right increases the range, This will affect the lift, and if you make the range too big it will be hard to control your height, a slight movement of your throttle will send your heli up way too fast and when you chop the throttle it will slam down. Another thing to remember is if you make the angle of the blades too aggressive too fast than it will over work the motor, and will not get your blades up to the proper rpm, and cause it not to climb. It will also cause the heli to spin harder to the left because the blades have too much restriction with a lot of pitch and are not cutting through the air smooth. The pzt ( pitch zero trim) is important to set right also. You want your heli to began lift around 60-70% throttle, you can do this by your pzt knob by turning it to the left to increase pitch, and to the right to decrease pitch. Something to know is if you make your heli lift at too low rpm it will cause it not to get up to rpm and cause it to fly heavy, and when you try to increase the throttle it will actually loose rpm, and altitude, and because the pitch will increase and the rpm will decrease the heli will began to spin more to the left and you will have to correct more with the left stick. The speed of the blades also helps create a gyro affect, and the faster they spin will make the heli more stable, if your blades do not get up to speed, flight will be more unstable. If the blades spin too fast before lift off it will cause the tail motor not to keep up with the blades, and cause your heli to spin to the left also. Try to adjust it around 60-70% is about perfect for smooth flight.

In "Normal" mode, from low throttle stick to 1/2 throttle, there will be no collective movment. the main rotor blades should be at zero pitch or thereabouts until you move beyond 1/2 stick. Above 1/2 stick the blades should go positive.

When you flip the to 3D position, the lower end (i.e. zero to negative) becomes available. The throttle also will not go below 1/2 in 3D mode and will increase from 1/2 throttle as you move the throttle/collective stick up or down.

The PLT knob controls the total pitch range. The PIT(PZT) knob controls the rate at which the pitch is mixed in vs throttle. Changing PIT(PZT) actually displaces the entire pitch setting, relative to throttle, without changing the overall pitch range.

If you have a total pitch range of 18 degrees with the PIT set so that you have zero degrees of pitch at 1/2 stick, you should have +9 at full throttle and -9 at low throttle (again, in 3D mode). If you tweak the PIT knob to add two degrees of pitch at 1/2 throttle, without changing the PLT knob, you will end up with +11 at full throttle/collective stick and -7 at low stick.

As you change one knob, you usually have to adjust the other. The goal being relatively constant main rotor RPM.

Neither of the knobs has any effect unless DIP switch #8 on the back of the transmitter is moved to the "Unlock" position. Once you unlock it, the factory settings are lost.

This is an entirely different approach to electronic pitch mixing than I have ever seen. It is found on Exceed, Venom, and Walkera. It works well and is pretty easy to set up, but it is just different.