Dual screen setup not remembered

Hi, I use Trinity R14.0.4 under Ubuntu 14.04 on a Dell Optiplex 990. My setup is dual screen (1 HDMI 27po, 1 DisplayPort 24 po) connected to a Radeon video card. The 24po is on my left and the 27po is in front (main screen). I tried tderandrtray, Trinity Control Center, System Settings to set things up with success. But each time I log out or reboot, the display settings are lost. Both screens show the same display (main) and are in reverse order (left/right). Is there a way to make Trinity remember my screen settings so I do not have to set things up each time? Thanks!