Firefox would be using the system time to get that information. Make sure the system time is correct and set to the proper display.

Are you using any Thai or other add-ons that can change the time display?

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Thanks for the response, but the year is still from the wrong calendar. The computer was purchased in Thailand but in the Mac OS I was able to choose the Gregorian calendar instead of the Buddhist calendar. This is the only place the wrong year is showing up. It isn't that big a deal. Just weird.

Separately and more importantly, I want to get all the old history from my old computer, but only a small portion of the "older than six months" history has been transferred through sync.

Hi, The time might be set in the Bios, you will need to boot into it and look.

How about the old way to do things instead of sync as they work.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

What Firefox locale do you use and what is the language of your Mac OS?

Firefox probably uses the OS settings for displaying dates.

See also this pref on the about:config page.

• intl.regional_prefs.use_os_locales

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

Thank you everyone. Actually the three months from the previous year in history still say 2560, but this isn't a big enough problem for me to dig into config or bios.

On the bright side I copied places.sqlite from my old computer after syncing the new stuff, and got all my old history so i can still search that. Now I think I need a history management add on to help delete multiple copies from facebook etc.

It would be best to store what you want in the Bookmarks Manager. If needed, you can create a new folder to store them.