Layouts are responsible for displaying component contents.
You should not modify original templates, just copy them to the templates directory, otherwise they will be overwritten on extension update.
Ensure that you turn off any cache settings to see any layout override changes that are made to the layout. Also, clear browser cache before viewing changes.
To modify any layout in component you should first copy it to Joomla Template directory e.g. if you would like to modify Item view you should copy:
This way the default component layout will be overwritten and can be safely modified.
It is important for auto update procedure which will overwrite original component layouts without touching your modified one.