How to check? Noise and Signal

During these days,
I checked a crypto exchanging market and facebook advertising.

According to the prediction or research, the system should follow the signal as per previous data. But mostly the system is not following the signal as per prediction.

ex. 1.
Facebook advertising

To promote the goods, normally, I using the facebook advertising.

1. Before setting up.
   Normally, I setting up the audience Insights.
2. Starting ad.
   Even I use same audience insight with same text and picture.
3. Not a same results (weekly based)
4. Why?
   Is there any valuable thing that I didn't expected?
5. Variable
6. Fixed

To be continue...