You just need to change the value in the appropriate section (prefork, worker, event) of:
/usr/local/apache/conf/extra/httpd-mpm.conf
and then restart Apache.
The value depends on available (free memory). Don't set the value too high. I recommend you to following:
1. Check how much free memory you have;
2. Find the most memory expensive http/apache process;
3. Divide free memory by the RAM usage of the most expensive http/apache process;
4. Divide the result by two.
Don't forget other services eat RAM too
I recommend you to check the following guide:
https://www.woktron.com/secure/knowledgebase/133/How-to-optimize-Apache-performance.htmlAlso, you can use:
/scripts/apache_mpm_calculator
to get values recommended by CWP.