Press a button of the toolbar of the rich text editor of a field, by the name of the button ("Bold", "Italic", "Bulleted List").
Examples
When I press the "Bold" button of the "Body" editor
When I press the "Italic" button of the "Body" editor
When we press the "Bulleted List" button of the "Body" editor
And I press the "Block quote" button of the "Body" editor
When press the "Bold" button of the "Description" editor
Pattern
When(/^(I |we )*press the "([^"]*)" button of the "([^"]*)" editor$/, …)
Part of @webship-js/backdrop-cms-steps (github.com/webship/backdrop-cms-steps), a step pack for Webship-js 2.0.x.