(Applies to: all versions of FusionBB)
You can easily adjust a user's registration date by using the following query:
UPDATE fbb_user_info
SET info_reg_date = 'xxxxx'
WHERE user_id = 'yyy'
Substitute the appropriate information for 'xxxxx' and 'yyy'. Please note that the date format is epoch time, which is the number of seconds since January 1, 1970. (More details on epoch time can be found at Wikipedia.org: Unix time. )
FusionBB Developer Joshua Pettit has a utility that can help you figure out the time: link to utility.
Have more questions or need help? Please post a message at the main FusionBB site.
(Thanks to FusionBB user Scorpio (Tony) for the inquiry and FusionBB Developer Josh Pettit for the information!)