To change the time when your login session gets expired go to the root of your phpmyadmin folder and find the file config.inc.php
Now search for this variable -> $cfg[‘LoginCookieValidity’]
In my example I changed it to 5 hours. You should also check the session.gc_maxlifetime in you php.ini file. The lowest value of those two will be in effect.
$cfg['LoginCookieValidity'] = 3600 * 5;