Make sure you use the AMD Cleanup Utility, or you can get the program Display Driver Uninstaller (DDU) search for how to restart your PC in safe mode and use that. Also use DDU to uninstall Nvidia drivers, if you had a card at one point, delete the drivers for it also.
They clean the old drivers so that nothing is around to mess up the new drivers, or older if you are installing those, either way always use the process of cleaning the drivers first, then install the drivers you want.
If you still have problems, use AMD Cleanup utility or DDU again and put the older drivers on again to see if your problems go away. That would point to something changing in the new drivers that is causing it, but hopefully cleaning the drivers will fix it for you, good luck!