Why does Render Scaling seem to change randomly

For me this seems to happen if I change anything in Radeon control panel - if I update drivers or any filters/shader settings. Next time I start it up it will reset to 100. I think msfs defaults it out when it detects any change in graphics settings coming from the driver. Plenty of times it will start up at 120 just as I want it to, but I check every time anyways.