Switch My Passport to backup new user account on Mac?

Not sure if I am explaining this very well. I used My Passport 2TB to backup my old Mac Book Pro and transferred the entire disk contents to my new Mac Book Pro 2013. Doing so created a second user profile on my new Mac. I then copied all must-have files to my new user profile already on the new Mac to start fresh. Days later, I connected My Passport to back up all and it was not recognized in the new user profile. I logged off and logged on to the second user profile and was able to access My Passport and complete a back up. All the folders and files from my new user profile were backed up successfully. Sadly, I have maintained this second profile and used this clunky backup process for the ensuing months. How do I switch My Passport to be recognized by and backup from my new user profile?  Thanks

Hello,

Make sure the drive is not password protected. 

Try installing the WD Security for Mac and try to unlock the drive