I have to re set home sharing each time I want to play my itunes/photos from my pc in apple tv, it doesn't save my settings

If the Apple TV isn't saving the settings try restoring the device.

If the iTunes library isn't saving the settings then with iTunes closed open the folder C:\Users\<User>\AppData\Roaming\Apple Computer\iTunes and rename the file iTunesPrefs.xml as iTunesPrefs (Old).xml then start iTunes. This will reset your settings in iTunes and should allow you home sharing preferences to be stored.

tt2