What is your goal with the dual monitors?
1) Is is Clone/Mirror Mode where both monitors show the exact same thing? This setting is limited by the smallest of your two monitors.
2) Is it Extended Mode where you want extra desktop space to work with? This setting will allow you to have different resolutions.
Both of these options are in you Destop & Displays window in CCC. Right click the little monitor on the bottom left and click either Duplicate or Extend.