Place the cursor where you want to insert the reference, click the toolbar option in the upper right corner, and a menu will appear. Put it on the Add Delete button and another menu will appear. Select the format in this menu and a drop-down menu will appear. Choose the one with the x square. So if you stay in word for a few days [1] will be in the upper right corner.

When applying again, enter [2] first, then use the mouse to select it, and click the X-squared button in the word toolbar (this button will appear in the toolbar after the first step. If there is this button before the first step, then the first step can also be used directly).