Ctrl-a/Ctrl-e are equivalent to Home/End (unless you're inside a screen session, which was a terrible choice of binding on their part).
You can set them to the vi ones instead with:
set -o vi
in my screenrc changes this to 'CTRL+spacebar', which I find much more sensible.
Ctrl-a/Ctrl-e are equivalent to Home/End (unless you're inside a screen session, which was a terrible choice of binding on their part).