Formater pour Mac

Try format it from a MAC computer.

Under Disk Utility highlight the WD external drive

from  “Volume Scheme” select 1 partition

from “Options” choose Master Boot Record and click OK.

You can name your Volume.

From “Format” choose MS-DOS (FAT) and click Apply to execute it.

Your WD hard disk drive should now be read and write by both MAC and PC computers.