OwnHelp Property
Specifies the source of the text that's displayed in a message box when a form field has the focus and the user presses F1. If True, the text specified by the HelpText property is displayed. If False, the text in the AutoText entry specified by the HelpText property is displayed. Read/write Boolean.
expression.OwnHelp
expression Required. An expression that returns a FormField object.
Example
This example sets the help text for the first form field in the current section to the contents of the AutoText entry named "Sample."
With Selection.Sections(1).Range.FormFields(1)
.OwnHelp = False
.HelpText = "Sample"
End With