Themepanel don´t keep the changes

Hello,

Try to clear all caches, deactivate all plugins, leave just Visual Composer active and test again, also verify the console for any errors while saving the settings on the Theme Panel, usually it displays a 403 or 404 error.
If the problem persist try to check system status: http://screencast.com/t/3Nv4Hrv6

Increase max_execution_time at least at 300 and the max_input_vars should be bigger than 2000. Those values are set in php.ini file so try to access it but note that some hosts may restrict the access at this file, if you don’t have access to it contact your host provider and let him know about this situation.
The WP_MEMORY_LIMIT from default-constants.php file it’s overwritten by the value from wp-config.php so try to modify the value from that file, here it’s a guide regrading this
http://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP

Let me know how it goes!

Thanks!