How Word edits important files in a copy way

1, open a random file. This file doesn't matter, it's just a tool.

2, click on the file in Word's menu bar, then select Open.

3, and then find your important document, will be a copy of it.

4, right click on the important document, then choose New.

5, pop-up a prompt box, click OK.

6, back to open the window, note here, click Cancel, instead of clicking Open.

7, this time to open a copy file, the changes made here will not affect the original file. Delete a little thing at random.

8, and then back to the original file to see if there is a change, deleted things are still in. This indicates that the file you just opened is a copy file.