You need to use a second paragraph style for the sub-items.
How do you use 2nd paragraph style?
I think you need to spend some time getting some basic training in how InDesign works.
Paragraph Styles are sets of attributes for the type in a paragraph. Each paragraph has a paragraph style applied, either of your choice, or the default [Basic Paragraph Style] if you don't define and choose something else. Every paragraph to which a particualr style is assigned uses the attributes defined in that style unless overridden by either a Character Style applied to slected text or by selecting text and manually changin the attributes (known as local formatting). By editing a style defineition you can reformat all the text to which that style was applied in a single step.