Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1968 the Official Secretary was re-titled an Administrator in 1968 and , since 1997 , Christmas Island and the Cocos ( Keeling ) Islands together are called the Australian Indian Ocean Territories and share a single Administrator resident on Christmas Island .
Simplified: The first Australian Official Representative arrived in 1958 and was replaced by an Administrator in 1968 . Christmas Island and the Cocos ( Keeling ) Islands together are called the Australian Indian Ocean Territories and since 1997 share one Administrator who lives on Christmas Island .