If you are an Admin/Owner you can register time for another user from the “Register Time” section.

In order to create time entries for other users, firstly you’ll have to enable the feature from Account settings>Register time for other users>Admins can create entries for other users.
After you have activated it, every time you open the register time dialog you should see an option to switch user on the top right.

timeneye-register-other-user