Just following on from the above post for AUD cash a/c buying US stocks I received the following advice from IB:
“Please know that due to ASIC regulatory restriction, IB LLC is not able to offer Australia clients FX conversion that will increase exposure in currencies that are not AUD. This means that you will not be able to convert from AUD into USD.
Having said that, you are still able to trade US securities and any debit cash balances will be converted as you have a cash account. Selling US securities will leave the proceeds in its denominated currency. For example:if you bought AAPL shares, we will automatically liquidate AUD into USD on your behalf as the purchase creates a debit cash in USD. When you sell AAPL shares, the proceeds will remain in USD.
to convert USD back into AUD, you will need to place a BUY trade. If you are using TWS, you can simply search for AUD.USD on your watchlist, right click and select Trade > Order entry > BUY > quantity is the equivalent of the AUD value.
Alternatively, you may also perform this conversion via TWS > Account > Account Window > Under “Market Value – Real FX Balance”, right click on USD and select “Close Currency Balance” > Select Variables and transmit order.”