The three fields should be plain text content controls. If you do this and then type in to each the text that you want as the default (empty) prompts you can then run the first macro to set the default text values.
Once the placeholder text is configured, you don't need to run that macro again. Then you can run the second macro to reset back to default.
Code:
Sub SetupCCs()
Dim aCC As ContentControl
For Each aCC In ActiveDocument.Range.ContentControls
aCC.SetPlaceholderText Range:=aCC.Range
Next aCC
End Sub
Sub ClearCCs()
Dim aCC As ContentControl
For Each aCC In ActiveDocument.Range.ContentControls
aCC.Range.Text = ""
Next aCC
End Sub