[Computer] How to view and change the default suffix name of a file under Win7

How do I view the suffix name of the default file under Win7 and change it?

For example, there is a file that is EXE, want to change to txt. However, you cannot change the suffix name if you cannot see it.

Double-click the Computer icon on the desktop, or any of the drive-letter interfaces, and tap the drop-down arrow to the right of organization on the left.

Then click on "folder and search Options", then you can see the settings button similar to XP: Cancel the "Hide extensions of known file types" before the √ OK.

[Computer] How to view and change the default suffix name of a file under Win7