If you do a lot of file shuffling on your Mac, you might get annoyed at the “Are you sure you want to change the extension?” warning that always pops up when you try to rename a file’s extension in Finder. Luckily, this warning is easy to disable. Here’s how.
First, click the Finder icon in your Dock to bring it to the foreground.
In the menu bar at the top of your screen, click “Finder.” In the menu that appears, select “Preferences.” (Or you can press Command+Comma on your keyboard.)
In “Finder Preferences,” click the “Advanced” button in the toolbar.
In the “Advanced” Finder Preferences section, uncheck “Show warning before changing an extension.”
It’s that easy. Close the Finder Preferences window, and the next time you change a file extension in Finder, you will no longer see a warning. Speedy fast!
By the way, if you always want to see file extensions on the Mac, just revisit “Finder Preferences” > “Advanced” and check “Show all filename extensions.” You’ll be slinging files like a pro in no time.