The manual settings inside the override.cfg must be restored every time you change resolution, if you choose fullscreen the vsync string will disappear, is still possible to use this option but you have to write it manually.
Here one configuration with full screen and vsync active (just copy and replace, follow indication below to understand the string)
Code:
[display]
window/size/viewport_width=3840
window/size/viewport_height=2160
window/size/mode=3
window/size/resizable=false
window/stretch/mode="viewport"
window/stretch/scale_mode="integer"
window/vsync/vsync_mode=1
change width and height to your resolution
window/size/mode= 1 background | 2 maximated window | 3 borderless fullscren (not exclusive),
in case of big resolution like mine the ui will be not resized that mean having a very small textbox, do not try to use fullscreen options with other resolution otherwise only the ui will be resized, not the game itself.
stretch mode and scale can't be changed, i mean you can but it will do absolutely nothing.
window/vsync/vsync_mode= gpu won't implode xD
Rn I'm working on a small universal mod for adding exclusive fullscreen so you won't need to change manually the resolution of your screen, this part is actually already completed however I'm having some trouble to integrate a focus switch (for exemple when you alt+tab), i'll let you know..
Why I'm doing this? Because programs like Magpie or other will use resources not necessary making the game even more heavy that already is.
UPDATE:
K..
Here it is, the tool is working fine but for now is in beta, some extra features don't work (like multi-monitor that require extra tools, i might integrate em in the package but for now there's no reason), you can get it from
here