I have the following javascript code which does google map autocomplete on different input textboxes that are parts of an address.
function startAutoComplete
The simplest way I've found to programmatically change the value of an Autocomplete input is to reinitialize the input field.
autocomplete = new google.maps.places.Autocomplete(address, option);
google.maps.event.addListener(autocomplete, 'place_changed', function() {
// populate your other text fields
...
// change the value of your autocomplete
address.value = place.name;
// reinitialize with new input value
autocomplete = new google.maps.places.Autocomplete(address, option);
}