›[T]to change figures dishonestly, often in order to get more money: fiddle your overtime/expensesThe report criticised officers who fiddled their overtime and tax inspectors who received tax-free bonuses.
›[I]to change something very slightly: fiddle with sthIf you fiddle with the figures in the investment column, you should be able to get your budget to balance.
fiddle the books›to dishonestly change a company's accounts or financial records: fiddled the books