Cmd+Tab App Switcher is on the wrong monitor

The App Switcher tends to follow where the Dock is located. Place your dock in the monitor where you want your app switcher to be displayed.

For example: if you have two monitors and the dock is on left side hiding then the app switcher will be on left monitor.

If the Dock is on the bottom, the app switcher will be on the monitor where the dock was most recently activated. You can test this by activating the dock and then the app switcher on each display.

BTW I am on Mavericks.

Just move your mouse pointer to the bottom of your primary display to cause the dock to pop-up (if hidden), and the App Switcher will pin to the display. If you activate the Dock on your secondary display, the App Switcher will pin to it. If you do not use the Pop-up Dock feature, just Click your Downloads icon on the dock in your primary display to move the App Switcher focus back to that display.

In OS X Mavericks, the task switcher is now shown on the screen that previously showed the dock (and in Mavericks this is both screens).

I don't really ever use the dock, but the task switcher jumped to my second monitor (Macbook) all the time anyway.

What worked for me was to move the dock from bottom of the monitor(s) to the right of my main monitor. The task switcher has not jumped back since i did that.