Light Building Not Working UE4.6

I need some expert assistance, please. I’m not sure if I messed up my settings somewhere along the line but the light building has stopped working.
I have subsequently disabled “Force No Precomputed Lighting” and now the light building is incredibly slow and quality is terrible.

I am a newbie to UE4 and will appreciate any assistance.

Is it the case that things worked properly before or are you just now trying to build your lighting and you’re getting poor results? Also would help to see some screenshots

temporary rename your project’s config folder. Unreal will create a new config folder with default settings. See if that fixes it and if it does maybe start to make changes and see what messes it up.