Custom Blog master template

How do i change or have different blog master template?. At the moment it is using post.php. I have created another template, and i cannot find it in the backend to use it with another blog post.

post.php

<?php include('../pwcms/runtime.php'); ?>
<?php perch_layout('blogstandard.header'); ?>

    <!--  change cols2-nav-right to cols2-nav-left if you want the sidebar on the left -->
    <div class="row">
    <div class="col-lg-12">
        <div class="primary-content">
<div class="col-12-lg mr-top-30">
<a href="/news">News</a> > <?php perch_blog_post_field(perch_get('s'), 'postTitle'); ?>
</div>

            <div class="post">
                <?php perch_blog_post(perch_get('s')); ?>


                <div class="meta">

                    <div class="tags">
                        <?php perch_blog_post_tags(perch_get('s')); ?>
                    </div>
                </div>

                <?php perch_blog_post_comments(perch_get('s')); ?>

                <?php perch_blog_post_comment_form(perch_get('s')); ?>

            </div>
        </div>

    </div>

    </div>

<?php perch_layout('standard.footer'); ?>

System diag

Perch Runway: 2.8.34
Production mode: Development (10)
Installed apps: content (2.8.34), assets (2.8.34), categories (2.8.34), perch_blog (5.0), perch_gallery (2.8.6), perch_members (1.5)
DB driver: PDO
DB tables: perch2_backup_plans (0), perch2_backup_resources (0), perch2_backup_runs (0), perch2_blog_authors (1), perch2_blog_comments (5), perch2_blog_index (1826), perch2_blog_posts (9), perch2_blog_posts_to_tags (2), perch2_blog_sections (2), perch2_blog_tags (3), perch2_blogs (7), perch2_categories (11), perch2_category_counts (4), perch2_category_sets (4), perch2_collection_index (0), perch2_collection_items (1), perch2_collection_revisions (1), perch2_collections (0), perch2_content_index (13210), perch2_content_items (1624), perch2_content_regions (91), perch2_gallery_albums (1), perch2_gallery_image_versions (6), perch2_gallery_images (1), perch2_members (13), perch2_members_forms (1), perch2_members_member_tags (42), perch2_members_sessions (5), perch2_members_tags (13), perch2_navigation (11), perch2_navigation_pages (28), perch2_page_routes (12), perch2_page_templates (53), perch2_pages (55), perch2_resource_log (4023), perch2_resource_tags (0), perch2_resources (598), perch2_resources_to_tags (0), perch2_scheduled_tasks (1), perch2_settings (32), perch2_user_passwords (2), perch2_user_privileges (40), perch2_user_role_privileges (68), perch2_user_roles (10), perch2_users (10)
Users: 10
PHPMailer: 5.2.21
App runtimes:
<?php
    $apps_list = array(
        'content', 
        'categories',
        'perch_members',
        'perch_blog',
        'perch_gallery',
    );
Scheduled tasks for perch_blog: delete_spam_comments (1440 mins)
Editor plug-ins: ckeditor, markitup
H1: 1faf3becf821a0912d27b8ef2383fb36
L1: 335813541ff8d23b27a57482926c5895
F1: 6a33f95eca3667f9e0c39bf5ca2980fe
headerColour: #000000
content_singlePageEdit: 0
helpURL:
siteURL: /
hideBranding: 1
content_collapseList: 1
lang: en-gb
update_2.8.31: done
headerScheme: dark
update_runway_2.8.31: done
latest_version: 2.8.15
on_sale_version: 2.8.34
perch_members_update: 1.4
perch_members_login_page: /members/login.php?r={returnURL}
dashboard: 1
hide_pwd_reset: 0
content_hideNonEditableRegions: 1
content_frontend_edit: 0
perch_blog_update: 5.0.1
perch_blog_post_url: /news/{postSlug}
perch_blog_site_name:
perch_blog_slug_format: %Y-%m-%d-{postTitle}
perch_blog_akismet_key:
perch_blog_max_spam_days: 0
perch_blog_comment_notify: 0
update_runway_2.8.32: done
perch_gallery_update: 2.8.5
update_runway_2.8.34: done
perch_gallery_bucket_mode: single
perch_gallery_bucket: default
perch_gallery_basicUpload: 0
logoPath: /pwcms/resources/bso-logo-2.png
PERCH_DEVELOPMENT: 10
PERCH_STAGING: 50
PERCH_PRODUCTION: 100
PERCH_SITEPATH: /var/www/vhosts/mywebsite/httpdocs
PERCH_SCHEDULE_SECRET: WjrzUvLhTIZMWb3L
PERCH_DB_USERNAME: intranetbso
PERCH_DB_SERVER: localhost
PERCH_DB_DATABASE: so_
PERCH_DB_PREFIX: 2_
PERCH_EMAIL_FROM: it@bluesquareoffices.com
PERCH_EMAIL_FROM_NAME: Blue Square Offices - Intranet
PERCH_LOGINPATH: /pwcms
PERCH_PATH: /var/www/vhosts/mywebsite/httpdocs/pwcms
PERCH_CORE: /var/www/vhosts/mywebsite/httpdocs/pwcms/core
PERCH_RESFILEPATH: /var/www/vhosts/mywebsite/httpdocs/pwcms/resources
PERCH_RESPATH: /pwcms/resources
PERCH_HTML5: 1
PERCH_TZ: Europe/London
PERCH_MEMBERS_SESSION_TIME: 720 minutes
PERCH_PRODUCTION_MODE: 10
PERCH_RUNWAY: 1
PERCH_ERROR_MODE: DIE
PERCH_DATE_LONG: %d %B %Y
PERCH_DATE_SHORT: %d %b %Y
PERCH_TIME_SHORT: %H:%M
PERCH_TIME_LONG: %H:%M:%S
PERCH_RUNWAY_ROUTED:
PERCH_STRONG_PASSWORDS:
PERCH_DEBUG:
PERCH_PREVIEW_ARG: preview
PERCH_TEMPLATE_PATH: /var/www/vhosts/mywebsite/httpdocs/pwcms/templates
PERCH_DEFAULT_DOC: index.php
PERCH_DEFAULT_EXT: .php
PERCH_RWD:
PERCH_HTML_ENTITIES:
PERCH_SSL:
PERCH_STRIPSLASHES:
PERCH_PROGRESSIVE_FLUSH: 1
PERCH_PARANOID:
PERCH_FORCE_SECURE_COOKIES:
PERCH_PASSWORD_MIN_LENGTH: 6
PERCH_MAX_FAILED_LOGINS: 10
PERCH_AUTH_LOCKOUT_DURATION: 1 HOUR
PERCH_VERIFY_UPLOADS:
PERCH_AUTH_PLUGIN:
PERCH_DB_CHARSET: utf8
PERCH_DB_PORT:
PERCH_DB_SOCKET:
PERCH_SESSION_TIMEOUT_MINS: 20
HOSTING SETTINGS

PHP: 7.0.16
Zend: 3.0.0
OS: Linux
SAPI: cgi-fcgi
Safe mode: not detected
MySQL client: mysqlnd 5.0.12-dev - 20150407 - $Id: b5c5906d452ec590732a93b051f3827e02749b83 $
MySQL server: 5.5.52-MariaDB
Free disk space: 43.15 GB
Extensions: Core, date, libxml, openssl, pcre, zlib, bz2, calendar, ctype, hash, filter, ftp, gettext, gmp, SPL, iconv, pcntl, readline, Reflection, session, standard, SimpleXML, sockets, mbstring, tokenizer, xml, cgi-fcgi, mysqlnd, bcmath, curl, dba, dom, enchant, fileinfo, gd, imagick, imap, intl, json, ldap, exif, mcrypt, mysqli, odbc, PDO, pdo_mysql, PDO_ODBC, pdo_pgsql, pdo_sqlite, pgsql, Phar, posix, pspell, redis, soap, sqlite3, sysvmsg, sysvsem, sysvshm, tidy, xmlreader, xmlrpc, xmlwriter, xsl, zip, ionCube Loader, Zend OPcache
GD: Yes
ImageMagick: Yes
PHP max upload size: 128M
PHP max form post size: 8M
PHP memory limit: 128M
Total max uploadable file size: 8M
Resource folder writeable: Yes
Session timeout: 24 minutes
Native JSON: Yes
Filter functions: Yes
Transliteration functions: Yes
PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
PP_CUSTOM_PHP_INI: /var/www/vhosts/system/mywebsite/etc/php.ini
PP_CUSTOM_PHP_CGI_INDEX: plesk-php70-fastcgi
SCRIPT_NAME: /pwcms/core/settings/diagnostics/index.php
REQUEST_URI: /pwcms/core/settings/diagnostics/?extended
QUERY_STRING: extended
REQUEST_METHOD: GET
SERVER_PROTOCOL: HTTP/1.0
GATEWAY_INTERFACE: CGI/1.1
REMOTE_PORT: 52800
SCRIPT_FILENAME: /var/www/vhosts/mywebsite/httpdocs/pwcms/core/settings/diagnostics/index.php
SERVER_ADMIN: it@bluesquareoffices.com
CONTEXT_DOCUMENT_ROOT: /var/www/vhosts/mywebsite/httpdocs
REQUEST_SCHEME: http
DOCUMENT_ROOT: /var/www/vhosts/mywebsite/httpdocs
REMOTE_ADDR: 10.0.0.21
SERVER_PORT: 80
SERVER_ADDR: 10.0.0.120
SERVER_NAME: mywebsite
SERVER_SOFTWARE: Apache
HTTP_COOKIE: cmsa=1; p_m=3ba834886c1b6523f62248ab72cf4218b0678815; PHPSESSID=5dj8n1g9o4p2dgrcfgfq99mqc6
HTTP_ACCEPT_LANGUAGE: en-US,en;q=0.8
HTTP_ACCEPT_ENCODING: gzip, deflate, sdch
HTTP_REFERER: https://mywebsite/pwcms/core/settings/diagnostics/
HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
HTTP_USER_AGENT: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36
HTTP_UPGRADE_INSECURE_REQUESTS: 1
HTTP_CONNECTION: close
HTTP_X_ACCEL_INTERNAL: /internal-nginx-static-location
HTTP_X_REAL_IP: 10.0.0.21
HTTP_HOST: mywebsite
UNIQUE_ID: WK1z21vE-lhOhlp7bdrUQAAAAMI
FCGI_ROLE: RESPONDER
PHP_SELF: /pwcms/core/settings/diagnostics/index.php
REQUEST_TIME_FLOAT: 1487762395.0866
REQUEST_TIME: 1487762395