Wrong Language appearing in notifications; need fix

That is not the droid, I mean, notifications I am referring to. My settings in my apple ID are and have always been US English. Everyone of my plethora of iPhones, desktops, laptops, all are set to US english, and have always been.

When I get and view the various pop up windows and notifications on all these devices, they are all in US English, except for the above mentioned MBP.

I have severe dozen other MBP running same OS and others with El Capitan, etc, no problems with any of these other devices , just the one. Again, Every preference setting is set for US English , yet when I get a notification that (for instance I am setting up a new iPhone) and when I am notified that another device has been added to my apple account, all the devices notify me of this change in US english except for the MBP that notify's me in Arabic, and I have turned my computer inside out, looking through the system, library files, etc, and still not able to fix it. I consider myself fairly MAC savvy, have been using MAC's since they were first on the market, have taken this problem to the "Genius" guys at three different Apple stores in this area, and they know less about how to fix or investigate this than I do, they are clueless, give me deer in the headlights stares.... they all tell me I should just get a new drive and start over.

I have looked through and analyzed the various pref files in the system, and library folders (both) and after trashing what I think will fix the problem, I am still seeing Arabic, but only with "notifications of new devices", all other notifications are in US english; email, updates, etc. are all in english even on the MBP that reveals the new device notifications in Arabic. Annoying, but not to the point of trashing my drive and starting over. Nonetheless, was curious if any one has the insight to fix this out there. I have even changed the preference language to another language, for instance Russian, restarted the MBP, and then switched back to US english, then restarted , and still the same. Still getting Arabic pop ups.