Not sure if anyone knows a fix for this but I have a Lenovo W510. I can manually change the brightness setting under power options but for some reason when I turn the computer off and back on the brightness (under AC power) is reset to maximum brightness. I read that some other manufacturers have this problem too. I'm thinking it is a Windows bug as I have the most up-to-date BIOS. Any suggestions on a fix?
More aboutscreen brightness refreshing
Try creating your own power plan and see if that solves the issue. If not, report back and we'll see what else we can come up with.