Got problem when my media upload is limited to 1MB only. First things first is to make sure that php.ini in our server set the upload_max_size with the size we like to allow our user to upload in our website.

upload_max_filesize = 64M
post_max_size = 64M
max_execution_time = 300

And if our server settings are ready, we need to set the file size upload on our multisite Settings to the size we intent.