WP Memory Limit won't increase. Can't import Demo content

Within the system diagnostics of the highend theme it says WP Memory Limit: 40 MB and i do not know why it isn’t increasing.

According to my phpinfo:

PHP Version 5.5.13

Directive Local Value Master Value
memory_limit 128M 256M

I wrote “php_value memory_limit 128M” in my .htaccess file, i wrote “define( ‘WP_MEMORY_LIMIT’, ‘128M’ );” in my wp-config.php and i wrote “define( ‘WP_MEMORY_LIMIT’, ‘128M’ );” in my wp-settings.php.

None of them increases the wp memory limit shown within the system diagnostics and importing demo content fails with a server error after some seconds.

What to do? Why the wp memory won’t increase? How to import demo content? Do i have to set other variables then wp memory?

Thanks!