Ok first of all you need to make sure you can see your toolbar. This means at the top of your document you will see icons such as 'view', 'fullscreen', 'outline', 'section' etc. If you can't see this go to 'view' and scroll down to show toolbar.
Once you can see the toolbar with all the little icons, go to the blue icon that says inspector. This should bring up a separate window box with many picture tabs such as a little page with folded corner. You need to click the one with a big 'T'.
There will then be tabs below that saying 'text', 'list', 'tabs', 'more'. Select 'more'.
You will see 'language' in bold text at the bottom to which you then choose 'Australian language'.
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