It can be fixed.
All of this can be done in a simpler way through the menus, but I'm not familiar with your desktop environment, XFCE. Waiting until the folks with the simple answer wake up is a good idea. But if you don't wish to wait, it can be done this way:
Open a terminal. Issue the command "vasm-legacy". (If that's not found, try "vasm")
Choose SUPER. (If you opened a "root terminal", that won't be there, but just read on 'til you get to the screen you do see) Input root/administrator password when asked.
(Here's where you would be already if you're already root)
Choose HARDWARE, then ZONESET
From your description of the problem, I think you should choose "UTC". If I'm wrong, do it again and choose localtime.
Now choose your timezone. Nevermind whether it has descriptions such as "POSIX" or not with it. Any of them that are the correct timezone will work.
The previous menu reappears.
Choose DATESET, follow the prompts.
From here you can exit vasm(-legacy) by continuing to press cancel.
You're back to terminal. Issue the command "date". Your proper date, time, and timezone should be displayed. If it's wrong, rerun vasm and make a different choice at the "localtime/UTC" point. Once you've got it right, it still may take until the next minute for your desktop clock to notice the change.
Changing the clock can cause some applications to misbehave. They think their files were written "in the future". Reboot can solve most of that. Worst case, shut down four hours and things will be back to normal at boot -- four hours being the difference between GMT and EDT.
On reboot, you may find yourself at a text login for the same reason. If so, just log in as root and issue "reboot".
If you have another operating system installed, especially Windows, and the time in VectorLinux doesn't match the time there, run vasm and choose differently at the "localtime/UTC" choice. VL will adapt fairly easily either way. Some other OS you have might not, so do it its way.
Like I said, you might wait for a simpler answer. It'll come.
Edited after posting to suggest "UTC" first. I had "localtime" before. Also added the notes about app and booting misbehavior. Sorry if you'd already read and tried this. Also added the note about other operating systems.