Hi James,
So much like any other property that you would change in the property sheet of a split form, we would only expect that change to be visible in the single form side.
The datasheet is provided sort of as-is, and isn't intended to reflect formatting changes in the property sheet.
In this case you're talking about the Display as Hyperlink property, but let's say for example, that you're updating the Back Color property of the same text box control to red.
What we would expect to see is that the text box would have a background of red in the single form and no background color change in the subform.
The short answer is that this is behavior we would expect to see.
Sorry James. That's probably not the answer you were looking for . . .
Kirk Beller
Microsoft Online Community Support