By default, WP-Filebase sets folder permissions to 777 and file permissions to 666. This gives best compatibility with all server setups, although it’s not the most secure setting.
To change the permissions that are applied during Sync, add the following two lines to your wp-config.php:
Put them above
/* That's all, stop editing! Happy blogging. */
All files will the be chmoded to 666 and category folders to 755 during the next sync.
Note that the numbers will be converted to octal numbers, so no leading 0 must be added like