By default, the Recent Documents list is generated automatically
by Word based on the documents that you open.
The list changes as you open different files.
However, if you frequently open a specific document,
you can pin it to the list.
By doing so, the document always remains on the
Recent Documents list until you remove it.
Click on the File Tab
to go to the Backstage View.
Click on Recent (You’ll notice that each document in the list has a pin icon beside it.)