Copy and Paste the following Code into the Form Module with appropriate changes to refer the Controls correctly:
Private Sub ServiceType_DblClick(Cancel As Integer)
Dim getval, rst As Recordset, bkmark As String
Dim bkmksave As String
bkmksave = Me.Bookmark
getval = Nz(Me![ServiceType], 0)
If getval = 0 Then
Set rst = Me.RecordsetClone
Do While Not rst.EOF
rst![ServiceType] = getval
bkmark = rst.Bookmark
Me.Bookmark = bkmark
Me.Bookmark = bkmksave
Set rst = Nothing
Enter the required change of Value in the ServiceType field and Double_Click on the field to make changes to all the records and come back to the record where you have made the change initialy.
You can see the changes happening on all the records one by one.