how to cancel out the gain of the differential amplifier used in cyton board for EEG data

I am using OPENBCI 21 channel cap with Cyton and daisy board. My PHD thesis is to collect data for emotion classification using random visual stimuli. I have developed a MATLAB software to separate and label the collected data for classification. I am getting from my OPENBCI device is too noisy .I have settled everything in GUI (Smoothing On, Notch filter 50, Bandpass 5 to 50 Hz) All channels are NOT RAILED and impedance is Green with all channels though the values are high but channels are GREEN as per vendor recommendations. Application of filters is in MATLAB code is not creating any difference in it. I have read about cancel out the gain of the differential amplifier used in cyton board ((https://ieeexplore.ieee.org/abstract/document/9862906)but unable to figure out the I am using OPENBCI 21 channel cap with Cyton and daisy board. My PHD thesis is to collect data for emotion classification using random visual stimuli. I have developed a MATLAB software to separate and label the collected data for classification. I have an issue that the data I am getting from my OPENBCI device is too noisy .I have settled everything in GUI (Smoothing On, Notch filter 50, Bandpass 5 to 50 Hz) All channels are NOT RAILED and impedance is Green with all channels though the values are high but channels are GREEN as per vendor recommendations.

Can anyone guide what to do .I am also attaching the images of my Eye closed of 2 minutes data. Application of filters is in MATLAB code is not creating any difference in it. in my case as when i opened my EEG device in idle mode a file saved is this...