If you upgraded your board from a 6.4 or prior, the old hard-coded time offset is preserved behind the scenes. That time offset is still used to alter the actual times stored.
When it comes time to display a time, it's written out by Javascript. The Javascript is what's actually responsible for adjusting the time according to the user preferences. If a user has Javascript turned off, they'll see the unadjusted original server-based time.