How to change author name (alias)

Thanks for your reply!
I wanted to display my name too on other articles that I wrote, so, if I change my name will be globally changed.
Searching the web, I found something that works somehow, but in case of a new update, I have to rewrite the functions.php in the theme.
The code is this:

add_filter( 'the_author', 'guest_author_name' );
add_filter( 'get_the_author_display_name', 'guest_author_name' );
function guest_author_name( $name ) {
global $post;
$author = get_post_meta( $post->ID, 'guest-author', true );
if ( $author )
$name = $author;
return $name;
}
if( !is_admin() ) {
add_filter( 'author_link', 'my_author_url' );
}
function my_author_url( $url ) {
global $post;
if( get_post_meta($post->ID, 'guest-author', true) ) {
if( get_post_meta($post->ID, 'guest_author_url', true) ) {
return esc_url( get_post_meta($post->ID, 'guest_author_url', true) );
} else {
return '';
}
}
return $url;
}

If you have another idea, please share.
Thanks!

Many thanks for your idea. Now I am not afraid of loosing my customizations.
Keep up the good work!