best practice Multihead, multi-screen, multi-display or multi-monitor-Debian 8
 

Hi,

(using Debian 8, 64-bit)
(all the monitors work and have output when connected)
(using 2 video cards; each with 2 display ports)

I inherited a system with four monitors.

Currently, I have the top two that work.

Would you please tell me what software I should use or what files to edit to be able to fully use my other 2 monitors? Should I run Multiple X-sessions? Or, is there a better option?

thank you.