How are you associating users to a post?
If you meant users as post authors you can try pre_get_posts
hook.
function user_author_pre_get_posts( $query ) {
$user_id = get_current_user_id(); // Get logged in user ID or pass specific user ID here
if ( ( $query->is_author() || $query->is_category() ) && $query->is_main_query() ) {
$query->set( 'author__in', $user_id );
}
}
add_action( 'pre_get_posts', 'user_author_pre_get_posts' );