@vimtips
also, if you know, what you search for and you have to change it every time:
open your document.
In NORMAL mode type
/searchstring (ENTER)
start at beginning reach the match.
Type
cw Newstring (ESC)
Now type in NORMAL mode for any next match
n
to change it to the same result type
. (dot)
through the entire document.
This useful if you need to change config-files, eg. "example.com" in your own domain.