Sorry, to clarify:
"Require Intel extensions" is /QxK etc.
"Use Intel extensions" is /QaxK etc.
That's the two settings that are right below each other, and I'm thinking those are what you mean.
You can combine more than one "Use" setting by adding it to the command line of the compiler, but AFAIK you cannot use more than one "Require" setting.
I did not select them in the menu, instead I added the relevant call to the command line.
HTH,
Simon.