The purpose of the sliders is to adjust how much control surface travel you get with joystick input. Some sticks require you to readjust the sliders to get the best control.
Example would be you are suffering from blackouts to often. You would adjust your pitch sliders so that you wouldn't get as much control deflection for the same amount of stick input, allowing you to use the same control movements you normally would. Also, say you are having trouble using your rudders to line up a quick shot, you input a small amount of rudder, but you get more movement than you want. Say the lower input was set to 10(first slider on the left) you would adjust it lower, starting at 2 or so, so that when you give the same amount of control input(rudder) the response is less, allowing more precise control.
A lot of people recommend setting aileron sliders all at 100% all the way across for instant roll input, and adjust the other two incrementally. Mine are set at default except for the rudder, which I start real low around 2 and work my way up proportionately.
I have heard some joysticks give more control input than others, and have heard of slider settings that go no higher than 50, or others starting at 50 and going up from there.
Ideally, when you have your sliders set at default and give 10% of stick movement, you should get 10% control surface movement. If you don't like the way your stick 'feels' you can adjust your sliders accordingly, but I think a lot of people just adjust their flying style unfortunately.
I hope I haven't confused you any, others might be able to explain it better than I.
ts
