on a standard keyboard, to get the symbol displayed at the top of a key you always use shift with the key (for the key at top left with 3 symbols on it you need to use the Alt-Gr key to get the third ¦)
And by the time you figure out how to use the arrow thingy there or five more posts following the one you wish to respond to as the "previous" one, so what's the point in using it: just mention the person's name.