This is UBB.threads 7.6.0 (2017) standard behavior. Timezone logic has not changed in any version since then.
https://www.ubbcentral.com/forums/ubbthreads.php/topics/260476/7-6-date-and-time-not-a-bugGo to Control Panel > General > Date & Time
Make the corrections for your forum time.
Because the data is cached for forum speed, the Islands are built and cached based on the "Timezone For Guests." To enable caching, it is not built on individual user custom settings.
Example:
This is a screenshot of the time of your post, as I view it in UTC-07:00 (Los Angeles)
This is the "Recent Topics Island" as cached, with Timezone For Guests set to UTC-04:00 (New York)
Further reading here
https://www.ubbcentral.com/forums/u...nchronizing-database-guest-post-time-bugand here
https://www.ubbcentral.com/forums/ubbthreads.php/topics/261933/calendar-functionAs a side note;
Did you just upgrade from 7.5.x -> 7.7.2? Your server was in a + tz. It now its been set to a 0 timezone. UTC is 0.