Hiding the Document Extension

By hiding the document extension, it cannot be changed. Thus, you can help prevent the extension from being damaged.
Follow the steps below.
1.
Select the [Settings] menu > [System Settings] on the Desktop Browser screen.
The [System Settings] dialog box is displayed.
2.
[Settings] > [System Settings] > [Common Settings] > [Display Settings] > [File Extensions Display]
Deselect [Display extensions].
3.
Click [OK].
Note
When extensions are set to be hidden, even if you add an extension at the end of the document name and save the document, the text you added is treated only as a part of the document name. However, if the document does not have an extension, the text you added is treated as an extension.
If you want to change the document extension, change the settings to display extensions once again.