You can select a time zone for each form so all submission times will be displayed with your preferred time zone. You can change the time zone setting by going to Settings > General tab under your form and choosing from the drop-down menu.
You can also set the time zone for your user profile. This will be applied to creation times on your forms and themes, and be used as the default time zone for any new forms. You can set your time zone preference on the "Profile" page in the admin tool.