If you want to change the default system sounds such as keyboard click, locking nd unlocking, button effect, etc... here is how I found to do it. YOU MUST BE ROOTED. Use ES File Explorer (free from market) Open and go to settings, scroll to bottom and check Root Explorer and Mount File System. Superuser will ask for permission, make sure to allow it. The default system sounds are found on the root of the phone, under System>media>audio>ui/ There you will find the sounds the system uses. Make sure to convert your sound you want to use to ogg format, then save your new sound to the phone somewhere by transfering it from the computer to a accessible folder on the phone. Then use ES File Explorer to navigate to the location of the new sound. Long press on the new sound then choose copy. Navigate to the ui/ folder location described above (may have to click on the dropdown at the top middle and choose ./) Click "paste" at the top to put the new sound in the ui/ folder. Then long press on the sound you want to replace and choose "rename". (I add "_original" to the file name so I remember and keep the original default sound) The long press on the new sound you want to use and click "rename" Rename the new file to what the original file name was. Exit from the program and reboot phone. (Will not apply until the phone is rebooted) Thats all there is to it! Works great for me.