The board default is to EST, which is GMT -5. Unfortunately, we live in the US, a country that insists on pulling that Daylight Savings Time bullshit. Since we are sprung forward, American is EST is currently GMT -4. I have been trying to find some sort of hack that'll account for Daylight Savings Time, but I haven't found one yet. So you currently have two options:

1) You can deal with it.
2) While the board default is GMT -5, you are by no means bound by it. You can edit your time settings in your profile.