I just managed to fix this issue.
1) create a custom resolution for the 2nd monitor.
2) After that, there the option of the resolution appears in the display setting
Now finally I can use my 2nd monitor.
Having the same problem here except that i have only one monitor. Display resolution in windows is grayed and the only way to change it is to go in the amd program and as you said is to create a custom resolution at 1920x1080. Problem is that you need a second monitor to be able to do that and hope that this second monitor will be detected. The amd application does not scale down to 640x480 and you cannot access the custom resolution button because you only see part of the display without being to schroll left and right . What a mess. I am upgrading from a Nvidia GTX1060 and never had a single problem like that. . Can't return this card (MSI 6600 xt) because newegg ha a no return, exchange only policy. Will never buy amd graphic card again
Thank you for your reply. Yes i did and no change. I tried to plug the computer on my 4k tv and it worked, seeing all the available resolutions in windows display parameters. For some bizarre reasons, it cannot detect my samsung pc monitor that has a FHD 60 hz display . I can also see in the graphic adapter popperties , in the event tab, that there is a device that has not started (amdwddmg). Is that related ? Any ideas ?