Without changing the view. how do you activate the default reviewing pane vertical

If you prefer to display the Reviewing Pane, follow these steps:
Make sure the Review tab of the ribbon is displayed.
In the Tracking group you see the Reviewing Pane tool. Click the down-arrow at the right of the tool. ...
Choose either Reviewing Pane Vertical or Reviewing Pane Horizontal, according to your desires.

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