1. Place the cursor at the position where you want to set the upper corner mark, click the right mouse button, and select the font command in the pop-up shortcut menu;

2. In the Font tab of the Font dialog box, select the superscript check box, as shown.

2. Set it by the superscript button on the font in the Start tab.

Place the cursor at the position where you want to set the upper corner mark, and click the superscript button on the font in the Start tab, as shown;

Third, through the shortcut key settings

Place the cursor where you want to set the upper corner mark, and press Ctrl+Shift+= at the same time.