Well a little more background on your site would help like are you integrating with anything?
If your integrating by example with vbulletin then if your server is in the USA you would need to put either 5,6,7,8 in the GMT option in global options to take the time back to GMT timezone. Cause Japan is -19 hours GMT and when you set your vbulletin profile to Japan they calculate their software from GMT. Both vbulletin and invisionboard do this. Darn brits. Everyone else calculates timezones from the server timezone and does offsets. Anyway I was in Palau last year so I know your the same timezone as that. Your 14 hours back from me since I am east coast. So it all depends where your server is located in USA to what you set so give us more info and we can help determine your issue