Fix Unable to change resolution in Immortals of Aveum,Fix Can't select resolution in full screen
Step 1) Change from borderless to Fullscreen
Step 2) Set your desired resolution in windows, in case of multiple monitors disconnect multiple monitors and then set the desired resolution in Fullscreen on main monitor.
Step 3) Open config file
ResolutionSizeX=1920
ResolutionSizeY=1080
LastUserConfirmedResolutionSizeX=1920
LastUserConfirmedResolutionSizeY=1080
and
DesiredScreenWidth=1920
DesiredScreenHeight=1080
LastUserConfirmedDesiredScreenWidth=1920
LastUserConfirmedDesiredScreenHeight=1080
In place of 1920 set whatever your screen resolution is (example 3840 for 4k)
In place of 1080 set whatever your screen resolution is (example 2160 for 4k)
Save the settings and then go to the fie properties and set it to read only