I can provide you some information on how Multicurrency works, dineshperera.

When turning on the Multicurrency, the existing bank accounts will be in your home currency by default. This is the reason why the bank transactions for USD and EUR account will still show in an AUD currency.

To link the bank accounts (USD and EUR) for automatic updates, you'll need to disconnect the existing ones.

Here's how:

1. Click Banking in the left menu.
2. Choose Banking.
3. Choose the bank account you need to disconnect and click the Pencil icon.
4. Place a checkmark for Disconnect this account on save option under File Upload Account.
5. Click Save and close.

For more details about disconnecting an account, you can check out this article: Disconnect or delete an account from the Downloaded Transactions page.

Then, create a new bank account that uses foreign currency for USD and EUR.

Here's how:

1. Click Accounting on the left menu.
2. Choose Chart of Accounts.
3. Click New.
4. In the Account dialog, choose the appropriate Account Type and Detail Type.
5. Enter a Name for the new account and an optional Description as well as any other required fields.
6. Choose the foreign currency to assign to the account from the Currency ▼ drop-down menu.
7. Click Save and Close.

Once done, add and connect the new bank accounts to automatically download the recent transactions.

For the old transactions (more than 90 days) that was dowloaded using the existing bank accounts, you can manually upload them into QuickBooks Online.

I have articles here about Multicurrency:

• Turn on and use multicurrency
• About Multicurrency
• How Multicurrency works
• Does QuickBooks Online support multicurrency?
• Assign a foreign currency or multicurrency to a customer

Just add some details below if you need anything else with Multicurrency. I'd be glad to help.