The taskbar appears on the wrong monitor after you change the primary monitor in Mac OX
If your taskbar appears on the wrong monitor after you change the primary monitor (= where the menu bar is) in the newest Mac OX, you ran into the same issue with me. I solved this issue by moving the dock position from the bottom to the right!
You can change the dock position by opening "Dock" in the "System Preferences".
I hope it helps.