Ubuntu 16.04 upgrade from 14.04 wrong conf file for multiple monitors

A few problems with the upgrade, but generally it went smoothly. I have a three monitor system run on a newish AMD card. Works fine in 14.04.3. I know all about how 16.04 doesn't allow flgrx anymore. I assumed it would install system AMD drivers correctly. I first got only one monitor, now two without doing anything - but they are each just copies of one another and the third is black. I need to once again have one large desktop. Computer lists that I only have one monitor and even that can not be adjusted properly. I hunted for the conf file that might be the problem and found my old conf file still there listing 'aticonf-monitor'-0/1/2 (and aticonfig-device, etc.), and assume this is my main problem - my old configuration file being used(?). However, I do NOT know what the new conf file should say nor the exact name of the conf file 16.04 will look for first [there are several in 14.04, and also now still in 16.04]. If anyone can help out, would be MUCH appreciated! All screens also do not show the desktop image I have selected when in Gnome fallback, though it does show it (weirdly) in just plain 'Gnome', but assume part of the problem could be the configuration file for the monitors. Thanks in advance. N.B. anyone have any idea when some better support of AMD will happen for Ubuntu 16.04?