I'll try to help out.
1 - What are the resolution of ALL the monitors you want to use; as an example mine are 1920x1080, 2560x1440, and 800x600
2 - What location(s) are your monitors lied out in; my monitors are configures as follows
Monitor 1 (1920x1080) then Monitor 2 2560x1440, then the MFD 800x600
3 - In Windows Config -> System Display, how are your monitors aligned. Mine are all aligned so the bottom of the monitors are aligned
What aircraft are you trying to use? A-10a, F15C, etc
I'm using a AMD Radeon 6700 XT, however, it shouldn't matter