I have just loaded my version and took screenshot.
There is no SD card mounted but it would show up in the left.
If it was there it would be an option to prepare noobs recipe. (Prepare partition get it ready for burning image next step.)
On the right you should have image to sd card option and search option to look for image on your Mac. Where ever you put it after you un packed.
Put it on your desktop so you can find it.
You then click IMG TO SD - Card and it will do it. it may ask for your user password for your mac.
If you dont see what i have in screenshot there is something wrong with version you downloaded.
Remember i am still on Mavericks if you are using El Capitan you may have to download a more recent version of Apple PI Baker.
There's no option to change it. Can write the image to an SD card and see what u get in the card. If u don't mind.