Webform Filter Component Roles
When creating/editing a field, scroll down to ELEMENT ACCESS. There you can set all the limitations based on roles.

If you use YML you can use something like:

'#access_create_roles':
    - administrator
'#access_update_roles':
    - authenticated
'#access_view_roles':
    - authenticated


Finally, if you want to change the accessibility of the webform, check the Access tab (admin/structure/webform/manage/FORM_NAME/access).