How do I change my system's default language?

Gnome 3 Classic
Gnome 3 Standard

Gnome 3 Classic

First thing you'll want to do is click on Applications on the top left corner and go to System Tools

Next click on settings inside System Tools (Settings) and a window will appear. Click on Region & Language and yet another window will appear.

Click on Language
Type the language you are interested in. In this example, we are using Hebrew
Click on Done
If shown, click on Restart
To add a language to your keyboard, Under Input Sources, click on the + sign
Type the keyboard format you want to add, then select it
Click on Done
If shown, click on Restart
To toggle between keyboard layouts, click on the upper right-hand section and choose the format.

NOTE: If the new language does not work after adding the layout, you may need to log out and back in, or reboot your computer

Gnome 3 Standard

First thing you'll want to do is click on Windows key on your keyboard, then type Language or Settings
Click on Region & Language

Edit media
Click on Language
Type the language you are interested in. In this example, we are using Hebrew
Click on Done
Under Input Sources, click on the + sign
Type the keyboard format you want to add, then select it
Click on Done
If shown, click on Restart
To toggle between keyboard layouts, click on the upper right-hand section and choose the format.