Roles can be setup so the users Location selection automatically defaults into Transaction records that they create.
Steps to edit or modify role:
1. Navigate to Setup > Users/Roles > Manage Roles > Edit users role.
2. Main/Top section > set Location Restrictions = none - default to own or own and subordinates only or own, subordinates or unassigned.
Users with the above role now have the Location set on their Employee record default into the Location field when creating Transaction records.
The same can be done for Class and Department by using the above steps and substituting Location for Class or Department.