First, go to the Multi Attribution report which is listed under the “Goals” category. In the top you can find a select field where you can change the number of days that should be considered prior to the conversion. By default, you can select 7, 30, 60 and 90 days.

You can configure which days should be available in your config/config.ini.php file like this:

available_days_prior_to_conversion = 7,30,60,90
default_day_prior_to_conversion = 30