Put the Quarter and Calendar Year controls in the Form Header, but don't try to use them as Default Values for bound fields. A Default Value is evaluated when the new record is created, and a reference to a header control can be unreliable in that context.

The method I would use is to set the fields in the form's BeforeInsert event. That event fires once, when the user starts entering a new record:

Private Sub Form_BeforeInsert(Cancel As Integer)
    Qtr = txtMasterValueQtr
    CY = txtMasterValueCY
End Sub

Of course, use your actual field/control names. If your bound fields are named Qtr and CY, and your unbound header controls are txtMasterValueQtr and txtMasterValueCY, the code above will copy the values into every new detail record.

Make sure the Quarter and Calendar Year fields are included in the form's Record Source and that the controls in the Detail section are bound to those fields. You can hide those detail controls afterward if you don't need users changing them individually.

Also, Employee Code probably should not be the primary key if an employee will have quarterly records more than once. You will eventually need more than one record for the same employee. I would normally use an AutoNumber ID field as the primary key, then use a unique index on EmployeeCode, Qtr, and CY if you want to prevent entering the same employee twice for the same quarter.

Thank you!