Follow these steps to add a password to an employee account.

From the Home Screen, click Settings, then click Employees. Then click on the employee you want to set a password for.

Then, click Edit Employee (also, the employee's username is in parentheses next to their name if needed):

Then, at the bottom of the screen find the section where the password can be input and confirm a new password:

After entering the (new) password twice, scroll back up to where you initially pressed Edit Employee and now click Save.