Right click on that partition and select Convert to APFS.Double check if the scheme is set to GUID Partition Map and set the format to Mac OS Extended Journaled.Select the external hard drive to convert to APFS and click the Partition button.Open Disk Utility and click on View at the upper left corner.In other cases, you can follow the steps to convert to APFS manually. If you install macOS High Sierra on an SSD drive of a Mac, then the drive will automatically convert into APFS file system. How to convert an external hard drive to APFS Most notable advantages are reliability and more resistance to data corruption due to bugs and power failures.
It brings with it a number of advantages over HFS+ a previous file system by Mac OS. APFS, short for Apple File System is a new file system implemented on Mac OS 10.13 High Sierra.
