Time zone shifted?
Until a few days ago my DL time zone was correctly set to midnight UK time. Then for no discernible reason it shifted to 6pm but appears to think I am in Saigon ("timezone":"Asia/Saigon").
I have not changed timezone, and I don't use the app. System = Windows 7 Professional and Firefox 38.0.5.
ETA - "DL" for clarity.
Duo is hopelessly confused about timezones. It thinks I'm in New York. Neither I nor my laptop have been anywhere near that time zone in the whole time time I've been here and my system time zone has also not been set to New York time. Where Duo got the impression that I'm in New York from is a total mystery to me.
The link at http://www.sevenforums.com/tutorials/944-time-zone-change.html shows how to change timezone for Windows 7, not sure about other versions but that site should be able to help.
If you have access to one of the Duolingo apps, doing an activity on the app is supposed to reset a Duolingo account’s timezone to match the mobile device’s timezone.
If you don’t have access to a Duolingo app, you could install the Greasemonkey extension in Firefox and then install the DuoTweak userscript to see if that would be able to reset the Duolingo account’s timezone.
(Note that I haven’t tried either method; this is just a summary of what I’ve found on the topic.)