The datetime is always stored in UTC then offset to server or local. For local offset it uses the users timezone specified within their Joomla user account (the params field for CB profile edit and registration). For server it uses whatever the global timezone setting is in Joomla. Edit your user within CB > User Management and check what your accounts timezone is. You can see the offset it's using when you hover the timeago usage long enough; it'll show as -OFFSET (e.g. -05:00) at the end of the datetime.

Even if you turn off user parameters you may still have a timezone saved to your user already. Edit your user within Joomla user manager and check what timezone is set for your account. Hover over the timeago longer as it'll show you the offset as part of the elements title. Not sure what more to suggest as this all works perfectly fine in my tests. Please ensure CB is completely up to date as there were some timeago issues awhile back that have long been fixed, but if you're not on latest build you may not have those fixes.