File Size restrictions are based on a server side setting, usually in php.ini. WA Extensions are installed locally to the development computer and do not impact the settings on the web server.
To increase the file upload size you need to edit your php.ini file.
upload_max_filesize = 64M
memory_limit = 96M
post_max_size = 64M
Change the values to whatever you require.
If you can't access a php.ini file you may need to contact your host to make these changes.
You may also be able to override the server settings using PHP and the ini_set command.