It's a good idea to keep your routers' configuration files on a server somewhere. You can then modify the configuration files using a convenient text editor and upload the files to your routers as necessary. One advantage to this procedure is that you can include comments within your configuration files. A comment is any line beginning with an exclamation point. For example:
! ! This is a comment. !
You can also type comments when you are configuring the router from the command line, but comments are never saved as part of the router's configuration. Therefore, when you try to view or save the router's configuration, the comments are gone.