When you get info on an app in iTunes, all the info is grayed out and you can’t change it. You can with music, but not with apps. I would love to create new categories for kids like math or reading so I can sort by those categories.
The only way I know of to do this is to make them into folders. In iOS 4 and up, press and hold an app to start re-arranging the home screen, then drag the apps onto each other to make a folder that you can name. Press the home button to exit this mode.
From what I know there is no way to change details on Apps (at least not without "hacking" the App). All informations are set by the developer and or Apple.
Also it wouldn't make much sense:
Whenever you update an App the old version is deleted and with it all the details you would have changed.