Unicode characters Ú and É are displayed incorrectly as Ú and É

I have a UTF-8 file with Spanish text, and some words with accent marks are displayed incorrectly in some of the software.

I believe my file is correct. For example, the name 'JESÚS' is encoded as 4A 45 53 C3 9A 53.

>>> b'\x4A\x45\x53\xC3\x9A\x53'.decode('utf-8')'JESÚS'

c39a is the correct UTF-8 encoding for \u00da, according to http://www.fileformat.info/info/unicode/char/00da/index.htm.

So, why some software renders it incorrectly?