Inquiry to Enquiry on button

Add this snippet to your site –

function wcfm_custom_0311_translate_text( $translated ) {
	$translated = str_ireplace( 'Inquiry', 'Enquiry', $translated );
	$translated = str_ireplace( 'inquiry', 'enquiry', $translated );
	return $translated;
}
add_filter('gettext', 'wcfm_custom_0311_translate_text');
add_filter('ngettext', 'wcfm_custom_0311_translate_text');

Add custom code(s) to your child theme’s functions.php
In case you do not have child theme then add those using this plugin – https://wordpress.org/plugins/code-snippets/