PC Issues After Windows 10 Clean Install

I had to do a clean install of windows 10 today because I had freezing issues which I have yet to see have gone with the clean install. I went into settings then system and recovery and selected reset and remove all files and settings and then it reinstalled windows 10, however my previous wallpaper was still there after the install. When it had finished the clean install I discovered problems I had when I first upgraded to windows 10. I managed to fix these issues before but now I can't remember how I fixed them. 1 of the issues is the brightness is backwards. I sometimes have to put brightness down to 0% to get full brightness. I have the settings set so that the screen brightness will be 80% when on battery and 100 when plugged in. For example if I boot the pc on battery the brightness is as it should be on 80% but when I plug it in the screen goes dark when it should be on 100%, so what I have to do is put the brightness to 0% in order to get full brightness??? The other problem is that shutdown now nearly takes a minute while it took like 10 seconds before the reinstall. This is another problem I had when i first upgraded but fixed it eventually but now i cant remember how. Can anyone help with these very annoying issues. Thanks for any replies.