Take a look at this—I hope it helps.
In the manual on page 21:2.1.3 “LVL N empty calibration" (N = 1 or 2) This function allows you to input the E “empty” distance, i.e. the distance between the reference point of the sensor and the minimum level (zero point).
2.1.4 "LVL N full calibration" (N = 1 or 2) This allows you to input the level F, i.e., the distance between the minimum and maximum levels.
You can get the manual here:
The explanations are clear.
There is also a video.
On page 27, section 2.1.7, you’ll find the basic principles for interference echo suppression.
If you are still stuck, E&H customer support is top notch. Just contact the representative in your area.