when i press control/home, instead of navigating to the start of my document,
a dialog box for Find and Replace (as in page number to go to, etc.) comes up

Left control/home says it is assigned to start of document, right
control/home says it is assigned to manage external csslinks, but the same F
& R box comes up for both. I don't know anything about managing css links,
and I don't use the F & R box.

Please tell me how to assign control/home (right AND left) to navigate to
the start of my document.