How to move Unity Launcher to a different monitor?

This is a bug:

• Launcher is shown on the wrong screen in some multi-monitor setups

(taken from the bug report)

Permanent workaround (requires logging back in again):

Edit ~/.config/monitors.xml, find the monitor you want the launcher to display on and change:

<primary>no</primary>

to:

<primary>yes</primary>

Now log out and log in again.

Temporary workaround (no logout required):

Open a Terminal window and...

1. Run xrandr to find the NAME of the output you would like to make primary.
2. Run xrandr --output NAME --primary && nohup unity --replace &

In Ubuntu 20.04, it's under Settings > Appearance > Dock > Show on:

If you are using Ubuntu 13.10 and up

On the same window where you set your screen orientation (System Settings>Displays:Launcher Placement) you can set the screen(s) on which the launcher show show up:

It isn't configurable in 11.04, but it is a known issue and I think I've read that it's fixed in 11.10. Not sure though.