How can I adjust the English version in Microsoft word?

Try this, in Word versions prior to Word 2007:

1. Press CTRL/A to select the entire document.
2. Click the Tools->Language->Set Language menu item.
3. Select the language you want in the list box.
4. If you want to make this the default language for future documents, click the Default button.
5. Click Yes in the message box.
6. Click OK.

In Word 2007:

1. Press CTRL/A to select the entire document.
2. Click the Review tab on the Ribbon.
3. In the Proofing section, click Set Language.
4. Continue as in Step 3, above.

That should do it.

If you are using the 2007 version of Word, you can click the Review tab. There's a button marked "Select Language", and you can specify English (Australia) there.