I have 4 minka air fans installed in my home at the same time, I need to update the frequency per fan so it's not interrupting with others when one is being used.

Based on my understanding all i have to do is change the frequency on the remote and by pressing Stop button on the remote for 5 seconds it should update the frequency. It's not working. What else can i do?

The receiver in the fan might be burnt out,it is at the ceiling in the large base or maybe the transmitter. Do you have fresh batteries in the transmitter?

You need to change the tiny DIP switch settings so each fan is set up differently. (Note that each pair of remote transmitters--the one in the fan body, held in a bracket above the light kit when you drop that down; plus the one on the wall switch or in a hand-held remote, must be set with the same combination.)
Our Minka Aire Churchill model has 4 DIP switches; I have seen Casablancas with 5.

Yes, If the receiver is the same model number one remote will work for both... (im assuming when you state remote you are referring to a hand held remote? or are you referring to a wall mount remote? Each ceiling fan comes with it's own electrical unit... I currently have some Minka concept fans if your interested in purchasing at a very good price or if I can help you out in any other way please feel free to contact me at payitforwardx2 @ GMAIL . COM I will be happy to help you in any way I can.