How do you change background color in the settings of JetBrain's IDE?

Console pane:

Settings / Editor / Colors & Fonts / Console colors

Console, background

Project view:

Settings / File colors

Add (Alt+insert), choose 'project files' scope, select a color.

Uncheck the 'Use in editor tabs' checkbox, make sure to check 'Use in project view'

Main view (general):

Settings / Editor / Color & fonts / General

Text, Default text

For changing the background of the editor goto File->Settings->Editor->Colors & Fonts->General->Text. You'll see an item called "Default text". On the right you will see a checkbox for background. Click on it and choose whatever color you prefer.

To change the editor background color in newer versions (after 2017) of Intellij Idea go to Settings > Editor > Color Scheme > General and then on the right side list expand Text and click on "Default text" then click on the color hex code to get the color wheel.