I'm not sure how to do it from the app; I haven't found any settings to adjust saturation. I have the same issue and am now trying the additional rain sensor for $69 on Amazon in which I just installed 6 days ago. I have 4 zones. Although the saturation is uneven between all 4, ranging from 95 72, 76 to 63, is been at a constant difference. It is my understanding that the sensor reads the moisture level in the zone it is placed and the estimates how long the system runs. And I think that each zone connected to it gets the same amount of run time hence causing the discrepancy. I think it's normal to have different moisture levels die to many natural factors such as shade, wind and different soil types within one yard. that you You can use 1 sensor to monitor up to 3 zones. Right now mine is positioned in the driest zone (63) not intentionally during placement, so if my theory is correct, then I'm going to split the difference and set it up in the zone that's been at 76 to try to even it out. I hope this works. 

Hi Junglim,

Currently Netro users are not allowed to reset the moisture level. We can help you reset the moisture level from our server side. Please let us know how you would like to reset the moisture level.

Thanks,

Netro Support

I would like to modify zone 2,3,4 and 8,9 to read same moisture readings as what zone 5 reads. That would help to water those zones properly. Not sure if you can locate my account this way, let me know if otherwise. Thanks!