Editor in source mode by default?

[.m.]

IIRC, it is not selected by default!

anyway, you can run below SQL queries (see this guidance if required)

ALTER TABLE `mybb_users` CHANGE `sourceeditor` `sourceeditor` TINYINT(1) NOT NULL DEFAULT '0';

UPDATE `mybb_users` SET `sourceeditor` = '0' WHERE `sourceeditor` = '1';