You can find the overtime settings under the General Settings, found in the "Settings" tab of the Agendrix Navigation bar on your left.
Daily (Blue square)
Add the daily threshold to reach before overtime is calculated. If there is no daily overtime, put 24 hours (meaning there will never be daily overtime calculated)
Weekly (Yellow square)
Add the number of hours required to hit weekly overtime.
PS: This setting will apply to all employees. You can override this setting individually in the employee's profile. (Bottom of the profile tab)