Classic British Flight Sim

Hi All,
I'm trying to do cutouts in Blender.
I can see and click on all the "Modifier/Difference/Object" items, but my screen doesn't show the bit that includes the "Apply" button, see attached screen shot.
How do I turn that on, please? It appears in on line tutorials, but I can't find it in V 2.90.1

They've hidden the button in another menu selection.
Thanks for reading, but seems problem solved.