I have two monitors. The left monitor is set as primary, but the Unity Launcher appears on the right monitor.
How can I move it to the other monitor?
This is a bug:
(taken from the bug report)
Permanent workaround (requires logging back in again):
Now log out and log in again.
Temporary workaround (no logout required):
Open a Terminal window and...
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.
A couple things to try. You can follow the instructions here.
In summary, run
Secondly, your monitors look like they might have the same connection type. If that's the case, you could try switching the cables they use to connect.
Lastly, if all else fails, you could just switch the physical location of the monitors. Maybe not the best solution, but also probably the simplest.
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:
for 11.10 there is no workaround, but there is a ppa on launchpad (unsupported) that fixes the issue.
You will need to relog for the changes to take effect.