What is changing?
When reporting on Ads performance the default attribution will change from 28 Day Click and 1 Day view to, 7 Day Click and 1 Day View.
If you set the 'Use unified attribution' to true, your conversion metrics attribution will use the attribution setting of your campaigns.
Please be aware that Facebook does not support aggregating conversion metric values across different campaign attribution settings.
What happens if I don't select any Conversion Window?
The Facebook default attribution values 1 Day View, 7 Day Click will be applied to measure the actions that occurred when a conversion occurred.
What will changing the Conversion Windows do?
The performance results will change in accordance to the attribution window which may increase or decrease results depending on the option chosen.