How do I rebind
1
as 4
and 4
as 6
without 1
becoming 6
?
Your question isn't clear at all. What do you want to achieve ?
If you want to insert "4" when you press 1:
(global-set-key (kbd "1") (lambda () (interactive) (insert "4")))
(global-set-key (kbd "4") (lambda () (interactive) (insert "6")))