@slikrik98,

Unfortunately, if the sensitivity is set to close range in the app, there is not much else that can be configured or adjusted via the App.

PIR sensors are a pretty basic technology that simply waits for a change in Infrared Signals as someone passes by the FoV. If your device is already seeing low IR interference and can easily see differences, it will be more likely to trigger. 

I have used standalone PIR sensors in the past, and they usually end up requiring very finicky placement or some sort of covering that could narrow/direct the FoV. You may attempt to find a well-matching tape such as white electrical to block an angle of the signal. 

I did just try to shorten the distance of one of my other PIR sensors with a piece of semi-transparent tape over the sensor, however, I am going to do some more testing to see if this can actually shorten the range, or just makes it less reliable.