Change ACF User Field selectbox returnlabel

ACF_user_field_selectbox_returnlabel.php

<?php

	/**
	 * Write the data to a file
	 *
	 * @param  [type] $filename [description]
	 * @param  [type] $data     [description]
	 * @return [type]           [description]
	 */
	function writedata( $filename, $data ) {

		if (!$filename) return;

		$upload_dir = wp_upload_dir();

		$settings = array(
									'upload_dir' => $upload_dir,
									'cache_dir'	 => $upload_dir['basedir'] . '/',
								);

		if (gettype($data) == 'array' ) $data = json_encode( $data );
	    if ( ! file_exists( $settings[ 'cache_dir' ] . "/{$filename}.txt" ) )  {
	        // write the file
	        file_put_contents( $settings[ 'cache_dir' ] . "/{$filename}.txt"  , $data );
	    	chmod( $settings[ 'cache_dir' ] . "/{$filename}.txt" , 0755 );
	    } else {
	        file_put_contents( $settings[ 'cache_dir' ] . "/{$filename}.txt"  , $data );
	    }

	}

$saved_results = array();
//add_filter( 'acf/fields/user/result/key=field_5c11624aa1b95' , 'show_users_field' , 50, 4 );
add_filter( 'acf/fields/user/result/key=field_5c11624aa1b95' , 'change_user_display' , 50, 4 );
//add_filter( 'acf/fields/user/query/key=field_5c11624aa1b95' , 'show_users_query' , 50, 1 );

function show_users_field( $result , $user , $field , $post_id ) {
    writedata( "user_result_{$post_id}" , array( 'result' => $result , 'user' => $user , 'field' => $field , 'postid' => $post_id) );
 	return $result;
}

add_filter( 'acf/fields/user/result/key=field_5c11624aa1b95' , 'change_user_display' , 50, 4 );

function change_user_display( $result , $user , $field , $post_id ) {
	$result = "User Email: " . $user->user_email ;
	return $result;
}

function show_users_query( $results ) {
    writedata( 'user_query' , $results );
 	return $results;
}