Use full Month Name instead of Abbreviation in List View

The output of the days of the week occurs in /includes/shortcodes/calendar.php.

I’m looking for the opposite…I’d like to use the 3-char abbreviation for months.

Just how to I gain access to that php file?

TIA,
David

Access your site via FTP.

If you don’t know how, here’s a tutorial – https://www.wpbeginner.com/beginners-guide/how-to-use-ftp-to-upload-files-to-wordpress-for-beginners/

Sorry but my question isn’t about uploading files (which I upload to the Media Library) but, rather, how to use 3-letter DoW abbreviations. It’d be great to use 3-letter month abbreviations as well.