The boss of Royal Bank of Scotland (RBS) has said it needs to change its behaviour "at every level" following a series of industry scandals.Ross McEwan, who took over from former Chief Executive Stephen Hester last year, said RBS needed to address and then clean up every aspect of how it treated customers.The bank, 81% owned by taxpayers, is facing a probe by the Financial Conduct Authority into accusations in November that it deliberately tried to drive businesses into collapse to strip their assets. It has denied the claims.In December, RBS received a £325m fine for alleged rigging of inter-bank lending rates. It was one of six financial institutions fined a total of £1.4bn by European regulators.In the same month, it agreed a £62m settlement over allegations of breaches of US sanctions. It has also been involved, along with rivals, in controversial issues such as alleged payment protection insurance mis-selling.Writing in British newspaper The Guardian, McEwan said people had told him RBS needed to stop doing things that were self-evidently in the bank's interest rather than that of its customers."I have heard the message loud and clear," he said. "RBS cannot start to claim to be a bank that always treats people fairly unless we stop doing those things that erode trust. We cannot start to claim we are renewing the bank unless we stop shirking our responsibilities to our shareholders - principally the British taxpayer."McEwan said RBS had forgotten what banking was about in a rush for growth and profit. "We sold them products like PPI which many didn't need, and in some cases didn't know they had," he said.McEwan, who plans to set out his strategy for the bank later this month, said RBS would reward loyal customers and "stop giving the best deals only to those who switch banks or apply online".He said RBS would also speed up its lending decisions and end bureaucracy.McEwan said debate about the bank's share price, its eventual re-privatisation and staff bonuses was likely to continue."We will have to continue to explain the costs we're facing for past misconduct," he added. "Our first priority, however, has to be to put customer banking back in the heart and soul of RBS."Shares in RBS rose 0.47% to 339.1p at 15:17 in London.PW