If you wish to find and replace the occurrence of a word, phrase, URL, or anything, and it's in several documents, don't think that it's a tedious task.
For eg: if you wish to replace the word "Hello" everywhere with "Hi", inside the directory "home/ucartztest/public_html/folder".
Run the following command:
find /home/ucartztest/public_html/folder -type f -exec sed -i 's/Hello/Hi/g' {} \;