Recorded times are wrong

Please read the user preferences documentation especially the part about timezones.

Don’t mix it up with the system specific configuration for new customers.

Cannot create user (already existing)

If you try to create a user and see an error message like The email is already used or The username is already used it is very likely, that this account was deactivated in the past. Deactivation does not remove a user from Kimai, it just hides it from all views and listing.

You can reactivate the account by going to the User administration, open the search and choose the value Both or No for the search option Active. The resulting list will include all deactivated users which can be reactivated by editing them and checking the Active checkbox.