Charles wants to know the best way to set up Time Machine on his Mac with macOS Mojave. Leo says that in the new OS, there is a new APFS file system, and there have been backup issues with Time Machine and others. He may need to use an external drive formatted with the old HFS file system. That will insure that if his internal drive dies, his backup is secure. Leo also recommends not using Time Machine as his primary backup system. He should make an image backup with SuperDuper.