If you see the second kanji above, your computer is using a non-Japanese kanji font. The second kanji is not recognized by Japanese (including your instructor) as the correct kanji for なおす. If your computer uses a non-Japanese kanji font, there are many other kanji that will appear "incorrectly." Please install a Japanese kanji font to display Japanese kanji.

Here is a way to correct the default font issues: How to display 直す.pdf