bash find and replace all files with specifc name with another file

sed -i 's/original/new/g' file.txt

echo dog dog dos | sed -e 's:dog:log:g'

#You can also use the above answer with appropriate slashes like
echo "grepper is a nice grepper" | sed "s/grepper/blow/g"

find . -name "boom.txt" -exec cp ~/replace.txt {} \;