Upfader question.....Adjust curve/slope?

I'm using Serato DJ Pro on my newly bought DDJ1000 SRT. I need to adjust the curve/slope on  the upfaders. The default setting doesn't work for me. I see in Serato DJ Pro > Settings > Mixer there is an upfader curve adjust option but it won't allow me to change it......What am I missing here? Can I adjust it directly on the DDJ?