hendrik on 11 Jan, 2019 02:11 PM
This is on macOS, right?
beaTunes stores all relevant files in the path ~/Library/Application Support/beaTunes/ (~/Library is hidden in Finder—the simplest way to find it is in Finder to open the menu item Go -> Go to Folder and enter ~/Library/Application Support/beaTunes/). If you want those files on your external hard drive, you need to make sure there is a symbolic link with the name ~/Library/Application Support/beaTunes/ to some folder on that external hard drive.
So in essence,
shut down beaTunes
copy the folder ~/Library/Application Support/beaTunes to /Volumes/YOUR_EXTERNAL_DRIVE/beaTunes
create a symbolic link on your internal harddrive named ~/Library/Application Support/beaTunes to the folder on your external hard drive (use the ln -s command from the command line, e.g. like this: ln -s /Volumes/YOUR_EXTERNAL_DRIVE/beaTunes ~/Library/Application\ Support/beaTunes)