One of the most annoying things about using the Mac in a multiscreen setup is that sometimes the Dock moves to a different screen when it is not your intention to do so.
Per Apple design, the Dock cannot be displayed simultaneously on multiple screens. To move the Dock to the bottom of the screen you would like it to be on:
- Set the Dock to bottom by using the Settings / Desktop & Dock / Position on screen option.
- Go to the screen where you want the Dock to appear.
- Move your cursor to the bottom edge of this screen.
- Wait for a few moments.
The Dock should appear on this screen and disappear from the other screen.