YES, I used the wrong name for the Command key, and for the folder All Photographs due to verbal similarities - ie Command-and-Control. and Pictures vs Photographs.
But "confused about Lightroom in general"? Nah, think again.
Well, if you are talking about the 'A'll Photograhs' collection (not folder) after all, then the answer is what has been given several times by several people already: The selection you made by pressing Cmd-A in your 'Francis' collection should remain when you switch to 'All Photographs'. One caveat: make sure images are not stacked in 'All Photographs' and make sure you do not have some active filter that filters out certain images.