external USB drive not detected

Hi,

Finaly my ReadyNAS is woking! but i have a series problem and need help please

I have attached my two external WD USB devices to the USB 3.0 ports (each 2 TB), and they are both password protected, when i plugged them in mycloud it did NOT detect them!! only after i removed the password mycloud was able to detect them. these two hard drives has vital info for me and i can't keep them unprotected, i can't rely on mycloud account password only, now anyone in my place can remove the external hard disks and access my data because they are NOT protected anymore.

my question: is there any way to keep my WD password and mycoude can detect them then i enter the password in order to open them?? so in case someone removed them from ReadyNAS he/she want be able to access the content of my the WD drive.

Please guys advise me what to do

Thanks