Word must be closed in order to add output styles. From the top menu click "EndNote X7" and then "Customizer..." from dropdown menu, to open the EndNote X18.104.22.168 Customizer Window (below). Click the "arrow" to the left of Output Styles to open the complete list. Select output styles by checking the box to the right of your desired discipline. This wil import all citation styles attributed to that discipline. In this example Behavioral Sciences was selected. Click the blue Next button. Click the blue Next button again. Click the blue Done button.
Now you need to configure the bibliography. With your EndNote library open, open a Word document and select "Configure Bibliography..." from the Bibliography dropdown menu in the EndNote toolbar. If you do not see the toolbar, click "View" from the top menu, then "Toolbars", and then "EndNote X7" to view it. This opens the EndNote X7 Configure Bibliography window. Click on the "Browse" button to view the EndNote X7 Styles window (below). Scroll down to see the added output styles. Notice, in this example output styles from the category Behavioral Sciences have been added. Select the specific style you want and click the blue "Choose" button, then click the blue "OK" button. Your document will now be formatted according to the style you selected. The style you selected will be added to the favorites list.