We can change the cookie time session feature at:
Settings->Features->General->Login cookie validity
I found the answer in here.. No activity within 1440 seconds; please log in again
EDIT:
This solution will work only for the current session, to change permanently do:
open config.inc.php in the root phpMyAdmin directory .
wamp folder: wamp\apps\phpmyadmin{version}\config.inc.php
ubuntu: /etc/phpmyadmin
add this line
$cfg['LoginCookieValidity'] = <your_timeout>;
Example
$cfg['LoginCookieValidity'] = '144000';