If this is the case, you can edit these details. To do this, open the working patterns tab in your company settings. 

Locate the working pattern you wish to edit and click edit working pattern. This will open the working pattern in the same format as when you first created it, allowing you to change the working hours etc. When you are ready, hit save working pattern. 

Once your working pattern has been assigned to at least one employee, it is no longer possible to edit the pattern as shown above. At this point, you will only be able to edit the working pattern's name and the holiday allocation/carryover limit values. To do this, follow the same steps as above.