MyBB 1.8.14 : update domain [fixed]

[Firnus]

Hi, I'm on MyBB 1.8.14,
(I update to 1.8.17 when i fix my issue.)

I try to move from one domain to another one.
The new domain are on PHP7

old somain and dir are : https example.org/example/forum
old somain and dir are : http sample.example.com/forum

I update $setting

$settings['bburl'] = "http://sample.example.com/forum";
$settings['cookiedomain'] = "sample.example.com";/* trying ".sample.example.com" too */
$settings['cookiepath'] = "/forum/"; /* trying "/" too */
$settings['homeurl'] = "http://sample.example.com/forum";

Move the deb, search for same settings in db and update the same way.
Then i try to connect to acp via http://sample.example.com/forum/admin/index.php : it's seems OK, but if i click on any link : (example /forum/admin/index.php?module=tools ) then i see the login url and can not connect with same user/pass.

Seems i have only _test session created.

What error i make ? Someting other to update ?

Another tool (coppermine gallerie) system work. 

Thank you

---

Sorry fixed :
inc/settings
$settings['cookiesecureflag'] = "0";