> That is already unchecked. The problem is that when I type the abstract its
> actually indented. But when I make I line break the next line starts a bit
> more to the left than the above abstract.
I've had this same problem and inserting \noindent in math input would not work for me. However, I was overthinking it. Put your cursor in front of the first word in your abstract, probably anywhere actually. Then left click and to paragraph setting. Simply uncheck the box that says intent paragraph! Hahaha this does the job and only effects the abstract.
Hope this helps whoever has this issue in the future!