Is this version 4.4.0?
I just used that feature yesterday. It may be hidden depending on what you’ve selected to be displayed.
In the 3D print workspace, in the Printer Setting box I select More Settings to open the bigger selection of settings. Then at the top there’s a drop down list with Default, Basic, Custom, Advanced and All.
If I select Advanced or All (presumably you could add it into Custom as well) there a line for ‘Support Placement’ that has options for Everywhere, or Touching Buildplate.
It seems like a lot of extra clicking to get to see what’s a pretty useful parameter, but I can understand why there are options for how complex people might want to go. The full list looks pretty overwhelming, especially if you’re new to this.