Ubuntu’s default GNOME desktop comes with a sidebar launcher (or dock). This launcher’s default position is on the left side. Most people leave it as it is, but a few like to change the dock position to the bottom.
Yes! You can totally change the Ubuntu launcher settings and change the dock position to the bottom or even to the right side.

Let me show how to do it.
Move the launcher in Ubuntu
Press the Windows button and bring up the activity area. Type ‘settings’ and click on the Settings application.

To change the dock position, go to Settings->Appearance. You should see some options under Dock section. You need to change the “Position on screen” settings here.
As you can see, you can change the launcher position to the left, bottom or right. The changes take place immediately. No need to log out or restart the system.

That was easy, right? It is one of the simplest ways to customize the dock in Ubuntu.
Recommended Read:

The Definitive Guide to Using and Customizing the Dock in Ubuntu
The dock is a handy utility and integral part of the Ubuntu ecosystems. Here are some essentials you should know about using the dock in Ubuntu.
Bonus Tip: Position of dock on a multiple monitor setup
If you have a multi-monitor setup, you can choose whether to display the dock on all screens or only one of the screens.

Change Unity Launcher position in Ubuntu 16.04 (for older versions)
You can change Unity Launcher position in following two ways:
Method 1: Command line way
Open a terminal (Ctrl+Alt+T) and use the following commands accordingly:
Move the Unity Launcher to bottom:
gsettings set com.canonical.Unity.Launcher launcher-position Bottom
Move the Unity Launcher to left:
gsettings set com.canonical.Unity.Launcher launcher-position Left
Method 2: GUI way (using Unity Tweak Tool)
Good news is that customization tool Unity Tweak Tool has made it easier to change the position of Unity Launcher in Ubuntu 16.04.
If you don’t have it installed already, use the commands below to install Unity Tweak Tool:
sudo apt-get install unity-tweak-tool
Once installed, open Unity Tweak Tool and click on Launcher:

In here, you can see the option to change Position here under the Appearance section.

You like it on the left or on the bottom or on the right?
I hope this post helped you to change the launcher position in Ubuntu. Do you like it on the bottom or on the left or maybe on the right side?
You can also check out other Ubuntu customization tips.
Didn’t work on Ubuntu 20.04, gnome-control-center 1:3.36.5-0ubuntu3.
The settings navbar on the left doesn’t have an “Appearance” entry.
That is weird, Dennis. The settings should be there. I hope you are using the default Ubuntu 20.04.
Anyway, you may change the settings from the command line:
gsettings set org.gnome.shell.extensions.dash-to-dock dock-position BOTTOM
If you want to put it back in the left, use this:
gsettings set org.gnome.shell.extensions.dash-to-dock dock-position LEFT
Hope this helps.
Did not work for Ubuntu 21.10
just tried it on 21.10 and it worked the same