Hi, welcome to the Community! 
If you right-click on an underlined part, does it look like this?
It’s possible the closing quotation marks are different than the opening ones–did you bring in your work from Word or another writing program?
You can change the quote settings in your work by going “Preferences…” → “Automatic Quotes”, and covert them all at once with the button found there.
You can darken the mood by right-clicking on the Pinboard and selecting “Pinboard background…” - there’s a few dark options there 
For the white page color, our friend @joey mentioned in an earlier post a way to put a colored rectangle behind your text here: Color of the paper in Papyrus Author - #2 by joey
With @joey’s tips you can write on something else than white, and remove the colored block from the Master Page before publishing.
To quickly go from the Master Page view back to the writing view after adding the background color, you can use the “Select All” command CTRL+A (CMD+A on mac) to select your text - I found it sometimes tricky to exit with the right-click on Master Page, if the graphic object covers all of it.
It’s a workaround, but hope it bridges the gap for you as long as we don’t have a dark mode. 