Open the document, double-click the mathematical formula that shows the problem, and the formula editor will start automatically. Click Style-Definition in the Formula Editor interface, and click Advanced in the pop-up Define Style dialog box.

At this time, you can see the font settings in the formula editor, paying special attention to the settings of variables, lowercase Greek letters and symbols. If your system does not support this font, the formula editor cannot display the mathematical formula correctly. You need to set it manually.

Generally speaking, the font "Times New Roman" is used for variables and the font "Symbol" is used for lowercase Greek letters and symbols. General windows systems install these two fonts by default.

What you see in Word is garbled, but what you see after entering the formula editor is the correctly displayed formula, and it becomes garbled after exiting the formula editor. In fact, this is because the formula is automatically displayed in the formula editor in the font supported by your system, but it is not updated in the word document. At this time, you only need to click "File-Update Document ..." or press the shortcut key "Ctrl+S" in the formula editor to update the formula font into the document. After exiting, you can see that the formula has been displayed normally.