How to permanently change the time in Ubuntu Server
Sounds like you have a timezone issue. The easiest way to fix this is to reconfigure the tzdata package sudo dpkg-reconfigure tzdata
There are alternative ways, like symlinking the correct zonefile from /usr/share/zoneinfo to /etc/localtime which will inform the system of the proper time:
ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
However, it's preferred to use dpkg-reconfigure
If your timezone is set up correctly, I think you have to adjust your hardware clock with the command hwclock.