Prestashop : Link to database cannot be established - php

Question

I have to handle the finishing of a prestashop website that is almost done and it's the first time I ever use prestashop, and I'm not very familiar with PHP and MySQL.
I have downloaded the site in local but When I launch MAMP Pro, and get to
http://localhost:8888/www/<mysite>/index.php
I get only this :
Link to database cannot be established: SQLSTATE[HY000] [1045] Access denied for user 'pshop'#'localhost' (using password: YES)
Prestashop's email says :
MySQL admin account : root
MySQL admin password : <adminpw>
MySQL database for Prestashop : prestashop
MySQL account for the Prestashop base : pshop
Password for the Prestashop MySQL account : <accountpw>
and in config/settings.php I have :
<?php
define('_DB_SERVER_', 'localhost');
define('_DB_NAME_', 'ps5');
define('_DB_USER_', 'pshop');
define('_DB_PASSWD_', '<accountpw>');
Actually I can see in phpMyAdmin that there are 2 db, one called prestashop and one called ps5. From what I can see they have the same definitions (same users, same clients) so I just changed ps5 into prestashop in config/settings.php, but none of them works anyway.
Is there another file where this appears and I should change it to harmonize everything ?
Should I change the db account password "just in case it's different" in phpmyadmin ? I'm a bit worried about possible consequences if it's not the right thing to do and i can not go back.
Is there a way in phpmyadmin to just *check what are the current passwords for accounts or db's?
Inside phpmyadmin > left pannel > prestashop (or ps5, same result) > right bar, "privileges" :
User "pshop" on client "localhost", type "global", has all privileges, but has no "Grant", and I can not set it to yes :
GRANT ALL PRIVILEGES ON *.* TO 'pshop'#'localhost'WITH GRANT OPTION MAX_QUERIES_PER_HOUR 0 MAX_CONNECTIONS_PER_HOUR 0 MAX_UPDATES_PER_HOUR 0 MAX_USER_CONNECTIONS 0;
#1045 - Access denied for user 'pshop'#'localhost' (using password: YES)
And,
mysql_error.log file in Mamp pro says :
160408 0:14:08 [Note] /Applications/MAMP/Library/bin/mysqld: Normal shutdown
160408 0:14:08 [Note] Event Scheduler: Purging the queue. 0 events
160408 0:14:08 InnoDB: Starting shutdown...
160408 0:14:09 InnoDB: Shutdown completed; log sequence number 50703588
160408 0:14:09 [Note] /Applications/MAMP/Library/bin/mysqld: Shutdown complete
160408 00:14:09 mysqld_safe mysqld from pid file /Applications/MAMP/tmp/mysql/mysql.pid ended
160408 10:10:21 mysqld_safe Starting mysqld daemon with databases from /Library/Application Support/appsolute/MAMP PRO/db/mysql
160408 10:10:21 [Warning] Setting lower_case_table_names=2 because file system for /Library/Application Support/appsolute/MAMP PRO/db/mysql/ is case insensitive
160408 10:10:21 [Note] Plugin 'FEDERATED' is disabled.
160408 10:10:21 InnoDB: The InnoDB memory heap is disabled
160408 10:10:21 InnoDB: Mutexes and rw_locks use GCC atomic builtins
160408 10:10:21 InnoDB: Compressed tables use zlib 1.2.3
160408 10:10:21 InnoDB: Initializing buffer pool, size = 128.0M
160408 10:10:21 InnoDB: Completed initialization of buffer pool
160408 10:10:21 InnoDB: highest supported file format is Barracuda.
160408 10:10:22 InnoDB: Waiting for the background threads to start
160408 10:10:23 InnoDB: 5.5.42 started; log sequence number 50703588
160408 10:10:23 [Note] Event Scheduler: Loaded 0 events
160408 10:10:23 [Note] /Applications/MAMP/Library/bin/mysqld: ready for connections.
Version: '5.5.42' socket: '/Applications/MAMP/tmp/mysql/mysql.sock' port: 0 Source distribution
Apache error log says :
[Fri Apr 08 00:14:10 2016] [notice] caught SIGTERM, shutting down
[Fri Apr 08 10:05:20 2016] [notice] Digest: generating secret for digest authentication ...
[Fri Apr 08 10:05:20 2016] [notice] Digest: done
[Fri Apr 08 10:05:21 2016] [notice] FastCGI: process manager initialized (pid 492)
[Fri Apr 08 10:05:21 2016] [notice] Apache/2.2.29 (Unix) mod_wsgi/3.5 Python/2.7.10 PHP/5.6.10 mod_ssl/2.2.29 OpenSSL/0.9.8za DAV/2 mod_fastcgi/2.4.6 mod_perl/2.0.9 Perl/v5.22.0 configured -- resuming normal operations
and php error log says nothing about today where i still have my problem
can it be a problem in my mamp pro config ?
• In mamp pro there is a MySQL tab and there is a button "change the root password", should I do it ?
It says "for safety reasons the password of the "root" mysql user must be changed when you connect to the internet"
but I'm just trying to work locally so I don't think I should do this ?
• Still in Mamp pro, I have a choice:
Execute Apache/MySQL server as a user :
jeremieg (Apache) / jeremieg (MySQL)
(jeremieg is my name and my mac book name)
or :
www (Apache) / mysql (MySQL) > This one is choosen by default
(none of them works anyway)
• Still in Mamp Pro :
- Default Apache port for http connections : 8888
- Default Apache port for https connections (SSL) : 8890
- MySQL port : 8889
But still, today when I clicked on "start the servers" in Mamp, because Apache was on but MySQL was off after I launched Mamp,
I had an alert saying port 80 was already used (strange because I was not asking for port 80), and that it could cause conflict with one of my virtual machines and so I should change the port; but I chose "Start the servers anyway" and it launched MySQL.
I also tried loading the index.php after disabling little snitch, just in case (and emptying cache), but it didn't change.