The Australian dollar did nothing to distinguish itself. There were no domestic economic data of any note and the Reserve Bank of Australia said nothing to liven things up. The main driver for the Aussie was investors' appetite for risk, which blew hot and cold. Ahead of the first US presidential candidates' debate they were nervous that Donald Trump was in the lead, with all that implies for international relations and trade: after it they were more relaxed. OPEC's surprise announcement of a cap on oil production was vaguely helpful to risk-appetite while grumbling concerns about Deutsche Bank were not.
In the end the Aussie was unchanged against the US and NZ dollars and it picked up nearly a cent against sterling, which continues to be hampered by uncertainty about what Brexit will mean and when the British government will reveal its plan.