こんにちは、閲覧ありがとうございます.
初歩的な質問かもしれませんが、どうぞよろしくお願い致します.

現在LaravelとPHPについて学習しております.
諸事情によりPHP5.6をつかってLaravelのプロジェクトを作成したいのですが、コマンドプロンプトからLaravel new プロジェクト名とコマンドを打ちLaravelのプロジェクトを作成しようとすると以下のようなエラーが出ます.

Crafting application... Loading composer repositories with package
information Installing dependencies (including require-dev) from lock
file Your requirements could not be resolved to an installable set of
packages.

Problem 1
- This package requires php >=7.0.0 but your PHP version (5.6.32) does not satisfy that requirement. Problem 2
- Installation request for doctrine/inflector v1.2.0 -> satisfiable by doctrine/inflector[v1.2.0].
- doctrine/inflector v1.2.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 3
- Installation request for laravel/framework v5.5.19 -> satisfiable by laravel/framework[v5.5.19].
- laravel/framework v5.5.19 requires php >=7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 4
- Installation request for swiftmailer/swiftmailer v6.0.2 -> satisfiable by swiftmailer/swiftmailer[v6.0.2].
- swiftmailer/swiftmailer v6.0.2 requires php >=7.0.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 5
- Installation request for phpdocumentor/reflection-docblock 4.1.1 -> satisfiable by phpdocumentor/reflection-docblock[4.1.1].
- phpdocumentor/reflection-docblock 4.1.1 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem
6
- Installation request for phpunit/php-code-coverage 5.2.2 -> satisfiable by phpunit/php-code-coverage[5.2.2].
- phpunit/php-code-coverage 5.2.2 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 7
- Installation request for phpunit/php-token-stream 2.0.1 -> satisfiable by phpunit/php-token-stream[2.0.1].
- phpunit/php-token-stream 2.0.1 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 8
- Installation request for phpunit/phpunit 6.4.3 -> satisfiable by phpunit/phpunit[6.4.3].
- phpunit/phpunit 6.4.3 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 9
- Installation request for phpunit/phpunit-mock-objects 4.0.4 -> satisfiable by phpunit/phpunit-mock-objects[4.0.4].
- phpunit/phpunit-mock-objects 4.0.4 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 10
- Installation request for sebastian/comparator 2.0.2 -> satisfiable by sebastian/comparator[2.0.2].
- sebastian/comparator 2.0.2 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 11
- Installation request for sebastian/diff 2.0.1 -> satisfiable by sebastian/diff[2.0.1].
- sebastian/diff 2.0.1 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 12
- Installation request for sebastian/environment 3.1.0 -> satisfiable by sebastian/environment[3.1.0].
- sebastian/environment 3.1.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 13
- Installation request for sebastian/exporter 3.1.0 -> satisfiable by sebastian/exporter[3.1.0].
- sebastian/exporter 3.1.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 14
- Installation request for sebastian/global-state 2.0.0 -> satisfiable by sebastian/global-state[2.0.0].
- sebastian/global-state 2.0.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 15
- Installation request for sebastian/object-enumerator 3.0.3 -> satisfiable by sebastian/object-enumerator[3.0.3].
- sebastian/object-enumerator 3.0.3 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 16
- Installation request for sebastian/object-reflector 1.1.1 -> satisfiable by sebastian/object-reflector[1.1.1].
- sebastian/object-reflector 1.1.1 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 17
- Installation request for sebastian/recursion-context 3.0.0 -> satisfiable by sebastian/recursion-context[3.0.0].
- sebastian/recursion-context 3.0.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 18
- Installation request for theseer/tokenizer 1.1.0 -> satisfiable by theseer/tokenizer[1.1.0].
- theseer/tokenizer 1.1.0 requires php ^7.0 -> your PHP version (5.6.32) does not satisfy that requirement. Problem 19
- laravel/framework v5.5.19 requires php >=7.0 -> your PHP version (5.6.32) does not satisfy that requirement.
- laravel/tinker v1.0.2 requires illuminate/console ~5.1 -> satisfiable by laravel/framework[v5.5.19].
- Installation request for laravel/tinker v1.0.2 -> satisfiable by laravel/tinker[v1.0.2].

Application ready! Build something amazing.

Composerの方で指定した使用PHPのバージョンは5.6です.
以前PHP7.0を使用していたときにはこのようなエラーは出ませんでした.
調べてみたのですが解決できず、どうかお力添えください.
足りない箇所はお教えいただけると幸いです.

【keyword】
- Windows10
- PHP 5.6.32 (cli) (built: Oct 25 2017 16:00:49)
- Laravel Installer 1.4.1
- Composer version 1.5.2 2017-09-11 16:59:25

【追記】
Laravelのバージョンは4.2.11を使用したいと考えております.
LaravelはコマンドプロンプトからComposer global require "laravel/installer=~1.1"と入力してインストールしています.