VBA form is not retaining data if a new form is closed with "X"

I've created a form in which a user can double click on a list box entry to open another form for info. When the user closes the new form I want the existing data on the original form to remain. In my current code, however, the original data is not retained if the user clicks "X" to close the new form.

Code:

Private Sub lstServiceHistory_DblClick (ByVal Cancel As MSForms.ReturnBoolean)
   frmJobDetails.Show
End Sub

How can I get the data to remain on the original form?