When you create a new record you want your combobox to default to ID 4.
Place the following in the form's current event
Code:
If Me.NewRecord = True Then
Me.ComboBoxName.Column(0) = 4
End If
If the checkbox is unticked you want your combobox to default to ID 4. Assuming you do not have the default value of your yes/no field assigned as "Null", this should work by placing it in the afterupdate event of your checkbox.
Code:
If Me.CheckBoxName.Value = 0 Then
Me.ComboBoxName.Column(0) = 4
End If
I have not tested this code. Based on your select query, your ID column should be index 0 when looking at it from this VBA perspective.