I have recently upgraded from a canon Rebel XTI to the Mark IV. Yes, I know- apples to oranges. I'm in the process of learning all of the wonderful functions that this new camera has to offer. One thing that just can't seem to master is selecting specific AF points. I can only select 1 or 2 at a time. How do I select specific ones, if I'm taking a group picture? I have read the manual and the white paper document but nothing will tell me in plain English, "Do [this] to select these points." Does anyone have experience with this? Can you help, pretty please?