I solved the issue using the solution in this page. there are many php.ini files in the ubuntu. you need to change the php configurations in all of them and restart both apache2 and php-fpm and you are done !!
https://askubuntu.com/questions/172217/apache2-php5-file-upload-and-post-max-size
https://askubuntu.com/questions/172217/apache2-php5-file-upload-and-post-max-size