When you deposit AUD to Swyftx, we convert it to USD for you in preparation for trading. To understand why we do this, you can read this article on AUD/USD conversions. The summary of that article, is because it allows us to offer lower fees and tighter spreads.
The difference you see from the amount you deposited, to the amount shown in the balance section is due to the foreign exchange rate. This rate is always shown to you on the deposit screen, and changes through out the day as the AUD/USD market moves.
When displaying your balances, the AUD value is shown for your convenience, however your account has actually been credited with a USD balance. You can see you actual USD balance by changing the base asset dropdown from AUD to any other.
But hang on, I thought there were no fees?
You're correct! There are no fees on deposits of $300 AUD and over. The difference is due to foreign exchange, and is incurred once, rather than on every trade. This allows us to provide you with lower trading fees and tighter spreads, which means you make back this difference on your first trade anyway.