We recommend that you allow employees to sign in and set their own work time preferences (prefer and dislike times). You can always choose to ignore them when using AutoFill or if you are manually assigning a shift.
Work time preferences are always good to know, especially when you are trying to find a last minute replacement.
Managers with permission to change company settings can set these employee permissions on your SETTINGS>Global Employee Permissions page.
You also can also allow employees to set their own Cannot Work times, but note that when they set those this will NOT affect any already assigned schedules. If you allow employees to set their own Cannot Work times, then the next time you use AutoFill, the system will not assign them to shifts that conflict with those Cannot Work times.