WordPress will automatically show the maximum upload size when you are uploading images form media and there are many way to change Media file upload size.
1:By theme function.php file
@ini_set( 'upload_max_size' , '70M' ); @ini_set( 'post_max_size', '70M'); @ini_set( 'max_execution_time', '500' );
2: By PHP.INI file from your hosting cpanel dashboard
upload_max_filesize = 70M post_max_size = 70M max_execution_time = 500
3: By .htaccess file in the root directory of your website.
php_value upload_max_filesize 50MB php_value post_max_size 50MB php_value memory_limit 50MB