To change how many days in advance an employee can pick up open shifts and see their personal schedule, click on the People tab. 

Find the employee's name in your list and click Edit to the right.

Under the Shift Details section, fill in the number of days in advance you want the employee to see their schedule in the Days in app box.

From now on, this employee will only be able to see that far out in their app. This will apply to both their own personal schedule and the open shifts you make available for them to pick up.