Use a button instead of input on forms

How do I use a <button> instead of <input type="submit"> on my forms? Thanks in advance.

This is the code I am using, its from the forms app examples:

<perch:input class="btn btn--large btn--center" type="submit" id="submit" value="Send" />

So instead of this:

<input id="form1_submit" name="submit" class="btn btn--large btn--center" value="Send" type="submit">

I need the html to be:

<button id="submit" class="btn btn--large btn--center" type="submit">Send</button>

Diagnostic Report:

Health check

 PHP 5.5.38 is up to date
 MySQL 5.5.5-10.0.28-MariaDB is up to date
 Image processing available
Summary information

Perch: 3.0, PHP: 5.5.38, MySQL: mysqlnd 5.0.11-dev - 20120503 - $Id: 15d5c781cfcad91193dceae1d2cdd127674ddb3e $, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (3.0), assets (3.0), categories (3.0), perch_forms (1.9), perch_gallery (2.8.8)
App runtimes: <?php $apps_list = [ 'perch_gallery', 'perch_forms', ];
PERCH_LOGINPATH: /cms
PERCH_PATH: /home/sites/websiteurl.com/public_html/cms
PERCH_CORE: /home/sites/websiteurl.com/public_html/cms/core
PERCH_RESFILEPATH: /home/sites/websiteurl.com/public_html/cms/resources
Image manipulation: GD
PHP limits: Max upload 64M, Max POST 64M, Memory: 128M, Total max file upload: 64M
F1: 0c66c2e1f82f9e0b7617b2cb8270f2c7
Resource folder writeable: Yes
HTTP_HOST: websiteurl.com
DOCUMENT_ROOT: /home/sites/websiteurl.com/public_html/
REQUEST_URI: /cms/core/settings/diagnostics/
SCRIPT_NAME: /cms/core/settings/diagnostics/index.php