Deprecation warnings

I ran my staging site with DEBUG set to true and I get deprecation warnings:

Deprecated: Required parameter $submit_result follows optional parameter $error in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-frontend.php on line 987 Deprecated: Required parameter $myfields follows optional parameter $args in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-functions.php on line 665 Warning: Cannot modify header information - headers already sent by (output started at /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-frontend.php:987) in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/assets/ext/wp-session/includes/class-wp-session.php on line 142 Warning: Cannot modify header information - headers already sent by (output started at /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-frontend.php:987) in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-admin/includes/misc.php on line 1380 Warning: Cannot modify header information - headers already sent by (output started at /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-frontend.php:987) in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-includes/functions.php on line 6878 Warning: Cannot modify header information - headers already sent by (output started at /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-content/plugins/youtube-showcase/includes/emd-form-builder-lite/emd-form-frontend.php:987) in /customers/e/9/c/publictalksoftware.co.uk/httpd.www/~~~/wp-admin/admin-header.php on line 9

I replaced my staging site with ~~~.

How do we fix?