Find all files with the extension .conf in the root directory, and for each of those files, execute a command to replace the string "VERSION='1.2.3'" with "VERSION='1.2.4'", and create a backup of the original file with the extension .bak.
find / -name '*.conf' -type f -exec sed -i.bak s/VERSION='1.2.3'/VERSION='1.2.4'/g {} \;