This application doesn't appear to be available anymore. I checked all the possible websites without success. However, to rename a document in a Windows operating system, locate it using Computer, then select it with a single click. Press F2 and type the new name of the document. You might not see the file extension because the option to hide them could be enabled. Changing a file extension manually will corrupt the file. Only apps should be used to properly save to another format or convert to another format.