Once the addin add-in is installed, your Microsoft Word shows a new Translate option in the Home ribbon. If, after installation, you cannot see this button please close and reopen Word.
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Translate complete documents
You can ask the addin add-in to translate the entire document:
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The add-in remembers your credentials in encrypted form.
If you want the addin add-in to "forget" your login, click the About link:
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