For settings under Basic, All Walk, and Search Settings, a user must have read access to the profile as well as read access to the specific setting in order to see the setting. Write access to the profile, and write and delete access to the setting, is needed in order to modify a setting. (Delete is needed to clear a setting, which may not be apparent from the form.) Note that some settings are grouped on a line, such as the Robots setting: permissions can be granted to the group as a whole (Robots), or only specific settings in the group (Robots - robots.txt or Robots - Meta). If a user has no read access to a setting, it will not be displayed on the page. If a user has no write access to a setting, it will be disabled (grayed out and not modifiable).