Took the plunge upgrade 1.39 to 1.56, admin missing options

Since happily running 1.39 for a long while, with Paypal updates, failing to take payments, finally had to close the shop.
PHP versions for paypal seemed to be an issue, higher required for Wordpress, 1.39 wanted lower version.

Host assisted in the earlier parts, now down to me and looking to the ZenCart forum.

First I created a duplicate of my database, lets call that data2, into data3, also a 3a & 3b in case anything got corrputed.
Changed database language to ut8_general_ci from latin1

Downloaded a zip of the new store, uploaded to site, and followed the install.php
It failed looking for the database #3, permissions and such like, but eventually round the block a few times it found #3
Some times it offered upgrade, other times only clean install but refered to upgrade in the text.
My host said the files had been modified, yet winmerge showed each download were identical.
The install upgraded the database from 1.39 all the way to 1.56 so it said, I took away the install.php folder and renamed admin.

Copied across my image files from the 1.39 /shop/ folders to the 1.56 /store/ folders, about half now show on the storefront.
There were no active files only jpg & gif.
States Down for maintenance, so looking at admin there are many issues here, so cannot go forward.

For some reason the 1.56 was still looking for the 1.39 custom folder so in myphpadmin edited;
phpmyadmin zen_languages edited custom/english to just english
UPDATE zen_languages SET directory = 'english' WHERE zen_languages.languages_id = 1;
That stopped it looking for my old /custom/english directory from 1.39.

Please select the HTML/Rich-Text editor you wish to use for composing Admin-related emails, newsletters, and product descriptions
No option to select HTML only plain text in the editor.

Despite removing in both coupon admin and the actual database I still get;
WARNING! Welcome Email Discount Coupon expires in -17903 days
Trying to amend the name of the store, I get at
.../store/admin/configuration.php?gID=1&cID=1&action=save
WARNING: An Error occurred, please refresh the page and try again.
This is the same trying to change any options including the Down for Maintenance to false.

My 1.39 /shop/ is still in its original folder, while the new 1.56 is in /store/ so no direct conflicts.
The 1.39 would still be connected to the #2 untouched database while 1.56 connected to #3, a copy of the #2 database.
Neither store is currently active. There are NO modifications, nothing added, just as it came in the zip file.

Apart from going back to the start again, what am I missing in the process of the upgrade.
Certainly didnt think this was going to be easy between these versions however happy to make customisations on the skin once it gets to work and in the main having my products and customers database within the 1.56 to work with.

I can write in HTML, but I do not edit PHP, so easy to make a mistake.

Example of the most recent log file (with ADMIN instead of my real adminname, thinking of google searches, and URL not a hyperlink in my signature)
Code:
[07-Jan-2019 08:11:45 UTC] Request URI: /store/ADMIN/login.php?camefrom=configuration.php&gID=20&cID=443&action=edit, IP address: 82.26.99.37 #1  mktime() called at [/home/nostalg/public_html/store/ADMIN/includes/functions/general.php:3294] #2  zen_date_diff() called at [/home/nostalg/public_html/store/ADMIN/includes/init_includes/init_errors.php:163] #3  require(/home/nostalg/public_html/store/ADMIN/includes/init_includes/init_errors.php) called at [/home/nostalg/public_html/store/includes/autoload_func.php:48] #4  require(/home/nostalg/public_html/store/includes/autoload_func.php) called at [/home/nostalg/public_html/store/ADMIN/includes/application_top.php:171] #5  require(/home/nostalg/public_html/store/ADMIN/includes/application_top.php) called at [/home/nostalg/public_html/store/ADMIN/login.php:9] [07-Jan-2019 08:11:45 UTC] PHP Warning:  mktime() expects parameter 6 to be integer, string given in /home/nostalg/public_html/store/ADMIN/includes/functions/general.php on line 3294