File | Settings | Project Settings | Code Style - YAML
Use this page to configure formatting options for YAML files. View the result in the Preview pane on the right.
On this page:
Tabs and Indents
|Use tab character||
|Indent||In this text box, specify the number of spaces (or tabs if the Use Tab Character check box is selected) to be inserted for each indent level.|
Click this link to reveal the list of languages to be used as the base for the current language code style. So doing, only the settings that are applicable to the current language are taken. All the other settings are not affected.
This link appears in the upper-right corner of the language-specific code style page, when applicable.
Click Reset to discard changes and return to the initial set of code style settings.