Lines or area in image levels: hard to see and use

Is there any way to make color lines showing image levels thicker, or make the area under the curve solid-colored as it was in earlier versions of ACR? Level adjustment which I was using for every image previously became almost useless to me in two most recent ACR versions. I did not ask earlier assuming there is no answer, but things got worse with a new 4k monitor (in combination with my senilis eyes) so I am extremely frustrated.

Thanks.