Apple Time Machine doesn't see my WD My Passport 2 TB using USB 3.0
The following command line, using tmutil, will force Time Machine to use your mounted disk as its destination. If the disk is mounted as /Volumes/MyBackupDisk, run:
sudo tmutil setdestination /Volumes/MyBackupDisk

P.S. tmutil is very useful, also for deleting backups and working over the &quot;operation not permitted&quot; error.