You can change the timezone your account is set to through the Account Settings page. The Account Settings page is accessed by clicking on your user's email address found in the top right corner, and the clicking on the Account link.
Next, click on the pencil image next to the Timezone to open the Edit Account Timezone screen.
Select a Timezone from the drop down menu, and then click Update Account button to save your changes.
Keep in mind that this will change the timezone for all users in your company.