1. With your document open, click on the Protect tool from the right pane.

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  2. From the Advanced Options or the Encrypt drop down menu, select Encrypt with Password.

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  3. Click Yes in the Applying New Security Settings dialogue box.

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  4. In the Password Security Settings window, ensure that the settings are as follows:
    a. Ensure that Require a password to open the document is selected.
    b. Under Compatibility, choose Acrobat X and later.
    c. Ensure that Encrypt all document contents is selected.
    d. Enter a strong password or passphrase in the Document Open Password field,
    and then click OK.

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  5. A dialogue box will prompt you to confirm the passphrase you have entered.  Reenter the passphrase and click OK.

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  6. A dialogue box will notify you that you must save the PDF file for the security settings to take effect. Click OK.

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  7. Save your PDF document by clicking File and then Save.
    Verify that (SECURED) appears in the title bar.

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