Scroll Bar and Current Value. Min and Max Values

thats the problem im trying to solve.

As default in example the scroll is selected by the user to current 100 (C7). min 50 and max 150.(has to be done manually)

if i change scenario as in C7 from 100 to say 1,000, then i need the default to change to 1,000, and the min to say 500 and max 1500. (higher current values requires higher min and max values)

thats the solution im looking for


thanks