Is there a way to change the default settings of screen scaling (for people with disabilities)?

Question

So Ubuntu provides some special settings for people with disabilities, evoked by SuperAlt8. There is a feature of screen scaling, which makes the screen appear larger or smaller (SuperAlt+ or SuperAlt- respectively). The problem is, if you want to enlarge your screen and press SuperAlt+, it goes way too large! So how could I set a bit different scale, say, 35% less of what it is now? Thanks!
P.S. I find this feature super useful for making screencasts.