[Koha] Help with query to find out these

I am using koha 3.1 on suse 11 with nozebra kindly help me out my modification log for a patron is not working fine. I need a query to fine out all these: 1.    The patron that pay, writeoff af fine in koha 2.    The query for all the patrons that have fines in the Library 3.    Query for a patron modification log. thanks