The normal way is to do it in the forms editor, but it is NOT recommended on production systems and breaks compatibility.
As these settings are all on the advanced tab, which is not shown as first tab, there is a safer solution.
Compare a record in the table isp_isp_user where the advanced settings are not set at all with a record where you set the spamfilter and antivirus settings to your needs. Then change the defaults of the fields in the mySQL table to reflect your new defaults with phpmyadmin. Make a backup of the database before!