Log into your Harmony account. Go to the "More Choices" section (the page that shows you pictures of the devices that you've programmed the remote for). From the left hand side of the menu, choose "More Options" from the device that you want to alter. Then select "Customize the Device, Sound, and Picture commands for this (i.e)TV". The next page will show you the remote with all the commands available. Scroll down towards the bottom of the page. Just past the gray bars you should the very 1st command that appears in your remote's LCD screen. You can then highlight the text on the left and change it to say whatever you want, then select the pull down menu to the right to "map" to the appropriate command. After you've made all your changes select save, then Update your Remote.

Hope that explains it well enough....