The borrower under a preauthorized loan may at any time pay all or any part of the unpaid balance in his or her account, or, if the account is not in default, the borrower may pay the unpaid principal balance in monthly installments. Minimum monthly payment requirements shall be determined by the licensee and set forth in the preauthorized loan agreement, except that the minimum monthly payment shall not be less than one and one-half percent of the average daily unpaid principal balance of an account having an average daily balance of more than three thousand dollars nor less than two percent of the average daily unpaid principal balance of an account having an average daily balance of three thousand dollars or less.