Hide or show the file extension for just one file

Why it happens

Every file has its own Hide extension checkbox, so you can hide .pdf on one file and show it on another. That checkbox only counts when Finder isn't set to show all filename extensions. With that Finder setting on, every extension shows, whatever each file's checkbox says.

How to fix it

1. Click the file once in Finder to select it.

2. Press Command-I, or choose File > Get Info, and open the Name & Extension section if it's folded away.

   Finder›File›Get Info›Name & Extension

3. Tick Hide extension to hide the ending, or untick it to show it. The name in Finder changes as soon as you click.

4. Close the Info window.

Still not fixed?

1. Checkbox does nothing? Choose Finder > Settings…, click Advanced and untick Show all filename extensions. That setting overrides each file's own choice.

   Finder›Settings…›Advanced›Show all filename extensions

2. If Hide extension is greyed out, the file may be locked. Untick Locked in the General section of the same Info window, or check you have permission to change the file.

   Finder›File›Get Info›General›Locked

3. If the box won't stay ticked for a file on an external or network drive, copy the file to your Mac and try there. Some drives don't keep this setting.

4. If it still won't change for files on your Mac's own drive after a restart, contact Apple Support.