: iTunes does not have a "Change Folder" button. To store backups on an external drive, you must use a Symbolic Link (Symlink) . This involves moving the "Backup" folder to your external drive and using a command (like mklink /d on Windows) to trick iTunes into thinking the folder is still in its default spot.
: While files are stored locally, they are often cryptic or encrypted. You typically need the iTunes app or third-party "Backup Extractors" to read the actual messages, photos, or database files within them. backup location itunes