By default auto-propagation is automatically enabled.
Select File > Options. The Options dialog box is displayed.
Select Editor > Auto-propagation from the navigation tree.
On the Auto-propagation page, select the Enable Auto-propagation check box under General and then select your preferred default auto-propagation options.
Click OK to save the settings and to close the Options dialog box.
Options Dialog Box: Auto-propagation
Auto-propagate Confirmed Translation