Hi, my sim get's brighter after looking down. I haven't installed anything except the PMDG 737, I just reset my computer so it's a clean install. Anyone have a fix? https://gyazo.com/1c7eb6379472e1ea84ada8ff920e7a95

Welcome to HDR... the D stands for dynamic lighting which means the sim will do things like make brights brighter under transitory conditions.  Go outside on a bright day and until eyes adjust it is really bright.  Go indoors and it is dark until eyes adjust.  You can adjust HDR to your preferences, and you should because the default settings are kind of aggressive in my opinion.

In addition: things should reset to normal after looking up again for a while (just as your eyes would in real life) but if the darker cockpit takes up a lot of the screen even when looking up this may not always happen. I had an A2A plane that was very black and dark and everytime I looked down at the cockpit and then up again the sky would stay too bright: in order to solve this I had to look left out of the window so the biggest part of my screen was filled with sky and then things would reset. It was quite annoying. BTW The sim get's brighter because when you look down at the cockpit the view adjusts to the changed situation: you should also see the cockpit itself become less dark. Without HDR the cockpit might be too dark. Anyway, as Dan said, adjust the settings to lower values. Or see if you like things withou HDR at all.

I don't see a problem in his linked video. You can see the HDR adjusting back to normal in barely more than a second when he looks up.

9 hours ago, Christopher Low said:

I don't see a problem in his linked video. You can see the HDR adjusting back to normal in barely more than a second when he looks up.

I can't see HDR adjusting back to normal. There is a clear difference between the start of the video and the end when it loops. I do wonder though how things would have looked if the video had been some 3 seconds longer: by then things should have been back to normal.